Author name code: sakao
ADS astronomy entries on 2022-09-14
author:"Sakao, Taro" 
------------------------------------------------------------------------  

Title: Quiet Sun Center to Limb Variation of the Linear Polarization
    Observed by CLASP2 Across the Mg II h and k Lines
Authors: Rachmeler, L. A.; Bueno, J. Trujillo; McKenzie, D. E.;
   Ishikawa, R.; Auchère, F.; Kobayashi, K.; Kano, R.; Okamoto,
   T. J.; Bethge, C. W.; Song, D.; Ballester, E. Alsina; Belluzzi,
   L.; Pino Alemán, T. del; Ramos, A. Asensio; Yoshida, M.; Shimizu,
   T.; Winebarger, A.; Kobelski, A. R.; Vigil, G. D.; Pontieu, B. De;
   Narukage, N.; Kubo, M.; Sakao, T.; Hara, H.; Suematsu, Y.; Štěpán,
   J.; Carlsson, M.; Leenaarts, J.
Bibcode: 2022ApJ...936...67R
Altcode: 2022arXiv220701788R
  The CLASP2 (Chromospheric LAyer Spectro-Polarimeter 2) sounding rocket
  mission was launched on 2019 April 11. CLASP2 measured the four Stokes
  parameters of the Mg II h and k spectral region around 2800 Å along a
  200″ slit at three locations on the solar disk, achieving the first
  spatially and spectrally resolved observations of the solar polarization
  in this near-ultraviolet region. The focus of the work presented here
  is the center-to-limb variation of the linear polarization across these
  resonance lines, which is produced by the scattering of anisotropic
  radiation in the solar atmosphere. The linear polarization signals of
  the Mg II h and k lines are sensitive to the magnetic field from the
  low to the upper chromosphere through the Hanle and magneto-optical
  effects. We compare the observations to theoretical predictions
  from radiative transfer calculations in unmagnetized semiempirical
  models, arguing that magnetic fields and horizontal inhomogeneities
  are needed to explain the observed polarization signals and spatial
  variations. This comparison is an important step in both validating and
  refining our understanding of the physical origin of these polarization
  signatures, and also in paving the way toward future space telescopes
  for probing the magnetic fields of the solar upper atmosphere via
  ultraviolet spectropolarimetry.

Title: Temperature and differential emission measure evolution of
    a limb flare on 13 January 2015
Authors: Bröse, M.; Warmuth, A.; Sakao, T.; Su, Y.
Bibcode: 2022A&A...663A..18B
Altcode:
  Context. Spatially unresolved observations show that the cooling
  phase in solar flares can be much longer than theoretical models
  predict. It has not yet been determined whether this is also the case
  for different subregions within the flare structure. <BR /> Aims:
  We aim to investigate whether or not the cooling times, which are
  observed separately in coronal loops and the supra-arcade fan (SAF),
  are in accordance with the existing cooling models, and whether the
  temperature and emission measure of supra-arcade downflows (SADs)
  are different from their surroundings. <BR /> Methods: We analysed
  the M5.6 limb flare on 13 January 2015 using SDO/AIA observations. We
  applied a differential emission measure (DEM) reconstruction code
  to derive spatially resolved temperature and emission measure maps,
  and used the output to investigate the thermal evolution of coronal
  loops, the SAF, and the SADs. <BR /> Results: In the event of 13
  January 2015, the observed cooling times of the loop arcade and the
  SAF are significantly longer than predicted by the Cargill model,
  even with suppressed plasma heat conduction. The observed SADs show
  different temperature characteristics, and in all cases a lower density
  than their surroundings. <BR /> Conclusions: In the limb flare event
  studied here, continuous heating likely occurs in both loops and SAF
  during the gradual flare phase and leads to an extended cooling phase.

Title: Demonstration of Chromospheric Magnetic Mapping with CLASP2.1
Authors: McKenzie, David; Ishikawa, Ryohko; Trujillo Bueno, Javier;
   Auchere, F.; Kobayashi, Ken; Winebarger, Amy; Kano, Ryouhei; Song,
   Donguk; Okamoto, Joten; Rachmeler, Laurel; De Pontieu, Bart; Vigil,
   Genevieve; Belluzzi, Luca; Alsina Ballester, Ernest; del Pino Aleman,
   Tanausu; Bethge, Christian; Sakao, Taro; Stepan, Jiri
Bibcode: 2021AGUFMSH52A..06M
Altcode:
  Probing the magnetic nature of the Suns atmosphere requires measurement
  of the Stokes I, Q, U and V profiles of relevant spectral lines (of
  which Q, U and V encode the magnetic field information). Many of the
  magnetically sensitive lines formed in the chromosphere and transition
  region are in the ultraviolet spectrum, necessitating observations
  above the absorbing terrestrial atmosphere. The Chromospheric
  Layer Spectro-Polarimeter (CLASP2) sounding rocket was flown
  successfully in April 2019, as a follow-on to the successful flight in
  September 2015 of the Chromospheric Lyman-Alpha Spectro-Polarimeter
  (CLASP). Both projects were funded by NASAs Heliophysics Technology
  and Instrument Development for Science (H-TIDeS) program to develop
  and test a technique for observing the Sun in ultraviolet light,
  and for quantifying the polarization of that light. By demonstrating
  successful measurement and interpretation of the polarization in
  hydrogen Lyman-alpha and the Mg II h and k spectral lines, the CLASP
  and CLASP2 missions are vital first steps towards routine quantitative
  characterization of the local thermal and magnetic conditions in the
  solar chromosphere. In October of 2021, we re-flew the CLASP2 payload
  with a modified observing program to further demonstrate the maturity
  of the UV spectropolarimetry techniques, and readiness for development
  into a satellite observatory. During the reflight, called CLASP2.1,
  the spectrograph slit was scanned across an active region plage to
  acquire a two-dimensional map of Stokes V/I, to demonstrate the ability
  of UV spectropolarimetry to yield chromospheric magnetic fields over
  a large area. This presentation will display preliminary results from
  the flight of CLASP2.1.

Title: Mapping of Solar Magnetic Fields from the Photosphere to the
    Top of the Chromosphere with CLASP2
Authors: McKenzie, D.; Ishikawa, R.; Trujillo Bueno, J.; Auchere, F.;
   del Pino Aleman, T.; Okamoto, T.; Kano, R.; Song, D.; Yoshida, M.;
   Rachmeler, L.; Kobayashi, K.; Narukage, N.; Kubo, M.; Ishikawa, S.;
   Hara, H.; Suematsu, Y.; Sakao, T.; Bethge, C.; De Pontieu, B.; Vigil,
   G.; Winebarger, A.; Alsina Ballester, E.; Belluzzi, L.; Stepan, J.;
   Asensio Ramos, A.; Carlsson, M.; Leenaarts, J.
Bibcode: 2021AAS...23810603M
Altcode:
  Coronal heating, chromospheric heating, and the heating &amp;
  acceleration of the solar wind, are well-known problems in solar
  physics. Additionally, knowledge of the magnetic energy that
  powers solar flares and coronal mass ejections, important drivers
  of space weather, is handicapped by imperfect determination of the
  magnetic field in the sun's atmosphere. Extrapolation of photospheric
  magnetic measurements into the corona is fraught with difficulties and
  uncertainties, partly due to the vastly different plasma beta between
  the photosphere and the corona. Better results in understanding
  the coronal magnetic field should be derived from measurements of
  the magnetic field in the chromosphere. To that end, we are pursuing
  quantitative determination of the magnetic field in the chromosphere,
  where plasma beta transitions from greater than unity to less than
  unity, via ultraviolet spectropolarimetry. The CLASP2 mission, flown
  on a sounding rocket in April 2019, succeeded in measuring all four
  Stokes polarization parameters in UV spectral lines formed by singly
  ionized Magnesium and neutral Manganese. Because these ions produce
  spectral lines under different conditions, CLASP2 thus was able to
  quantify the magnetic field properties at multiple heights in the
  chromosphere simultaneously, as shown in the recent paper by Ishikawa
  et al. In this presentation we will report the findings of CLASP2,
  demonstrating the variation of magnetic fields along a track on
  the solar surface and as a function of height in the chromosphere;
  and we will illustrate what is next for the CLASP missions and the
  demonstration of UV spectropolarimetry in the solar chromosphere.

Title: Mapping solar magnetic fields from the photosphere to the
    base of the corona
Authors: Ishikawa, Ryohko; Bueno, Javier Trujillo; del Pino Alemán,
   Tanausú; Okamoto, Takenori J.; McKenzie, David E.; Auchère,
   Frédéric; Kano, Ryouhei; Song, Donguk; Yoshida, Masaki; Rachmeler,
   Laurel A.; Kobayashi, Ken; Hara, Hirohisa; Kubo, Masahito; Narukage,
   Noriyuki; Sakao, Taro; Shimizu, Toshifumi; Suematsu, Yoshinori; Bethge,
   Christian; De Pontieu, Bart; Dalda, Alberto Sainz; Vigil, Genevieve D.;
   Winebarger, Amy; Ballester, Ernest Alsina; Belluzzi, Luca; Štěpán,
   Jiří; Ramos, Andrés Asensio; Carlsson, Mats; Leenaarts, Jorrit
Bibcode: 2021SciA....7.8406I
Altcode: 2021arXiv210301583I
  Routine ultraviolet imaging of the Sun's upper atmosphere shows the
  spectacular manifestation of solar activity; yet we remain blind to
  its main driver, the magnetic field. Here we report unprecedented
  spectropolarimetric observations of an active region plage and
  its surrounding enhanced network, showing circular polarization in
  ultraviolet (Mg II $h$ &amp; $k$ and Mn I) and visible (Fe I) lines. We
  infer the longitudinal magnetic field from the photosphere to the
  very upper chromosphere. At the top of the plage chromosphere the
  field strengths reach more than 300 gauss, strongly correlated with
  the Mg II $k$ line core intensity and the electron pressure. This
  unique mapping shows how the magnetic field couples the different
  atmospheric layers and reveals the magnetic origin of the heating in
  the plage chromosphere.

Title: Estimating the Temperature and Density of a Spicule from 100
    GHz Data Obtained with ALMA
Authors: Shimojo, Masumi; Kawate, Tomoko; Okamoto, Takenori J.;
   Yokoyama, Takaaki; Narukage, Noriyuki; Sakao, Taro; Iwai, Kazumasa;
   Fleishman, Gregory D.; Shibata, Kazunari
Bibcode: 2020ApJ...888L..28S
Altcode: 2019arXiv191205714S
  We succeeded in observing two large spicules simultaneously with the
  Atacama Large Millimeter/submillimeter Array (ALMA), the Interface
  Region Imaging Spectrograph (IRIS), and the Atmospheric Imaging Assembly
  (AIA) on board the Solar Dynamics Observatory. One is a spicule seen
  in the IRIS Mg II slit-jaw images and AIA 304 Å images (Mg II/304 Å
  spicule). The other one is a spicule seen in the 100 GHz images obtained
  with ALMA (100 GHz spicule). Although the 100 GHz spicule overlapped
  with the Mg II/304 Å spicule in the early phase, it did not show any
  corresponding structures in the IRIS Mg II and AIA 304 Å images after
  the early phase. It suggests that the spicules are individual events and
  do not have a physical relationship. To obtain the physical parameters
  of the 100 GHz spicule, we estimate the optical depths as a function
  of temperature and density using two different methods. One is using
  the observed brightness temperature by assuming a filling factor,
  and the other is using an emission model for the optical depth. As a
  result of comparing them, the kinetic temperature of the plasma and
  the number density of ionized hydrogen in the 100 GHz spicule are
  ∼6800 K and 2.2 × 10<SUP>10</SUP> cm<SUP>-3</SUP>. The estimated
  values can explain the absorbing structure in the 193 Å image, which
  appear as a counterpart of the 100 GHz spicule. These results suggest
  that the 100 GHz spicule presented in this Letter is classified to a
  macrospicule without a hot sheath in former terminology.

Title: Achievements of Hinode in the first eleven years
Authors: Hinode Review Team; Al-Janabi, Khalid; Antolin, Patrick;
   Baker, Deborah; Bellot Rubio, Luis R.; Bradley, Louisa; Brooks,
   David H.; Centeno, Rebecca; Culhane, J. Leonard; Del Zanna, Giulio;
   Doschek, George A.; Fletcher, Lyndsay; Hara, Hirohisa; Harra,
   Louise K.; Hillier, Andrew S.; Imada, Shinsuke; Klimchuk, James A.;
   Mariska, John T.; Pereira, Tiago M. D.; Reeves, Katharine K.; Sakao,
   Taro; Sakurai, Takashi; Shimizu, Toshifumi; Shimojo, Masumi; Shiota,
   Daikou; Solanki, Sami K.; Sterling, Alphonse C.; Su, Yingna; Suematsu,
   Yoshinori; Tarbell, Theodore D.; Tiwari, Sanjiv K.; Toriumi, Shin;
   Ugarte-Urra, Ignacio; Warren, Harry P.; Watanabe, Tetsuya; Young,
   Peter R.
Bibcode: 2019PASJ...71R...1H
Altcode:
  Hinode is Japan's third solar mission following Hinotori (1981-1982)
  and Yohkoh (1991-2001): it was launched on 2006 September 22 and is in
  operation currently. Hinode carries three instruments: the Solar Optical
  Telescope, the X-Ray Telescope, and the EUV Imaging Spectrometer. These
  instruments were built under international collaboration with the
  National Aeronautics and Space Administration and the UK Science and
  Technology Facilities Council, and its operation has been contributed
  to by the European Space Agency and the Norwegian Space Center. After
  describing the satellite operations and giving a performance evaluation
  of the three instruments, reviews are presented on major scientific
  discoveries by Hinode in the first eleven years (one solar cycle long)
  of its operation. This review article concludes with future prospects
  for solar physics research based on the achievements of Hinode.

Title: Comparison of Scattering Polarization Signals Observed by
CLASP: Possible Indication of the Hanle Effect
Authors: Ishikawa, R.; Trujillo Bueno, J.; Uitenbroek, H.; Kubo, M.;
   Tsuneta, S.; Goto, M.; Kano, R.; Narukage, N.; Bando, T.; Katsukawa,
   Y.; Ishikawa, S.; Giono, G.; Suematsu, Y.; Hara, H.; Shimizu, T.;
   Sakao, T.; Winebarger, A.; Kobayashi, K.; Cirtain, J.; Champey, P.;
   Auchère, F.; Štěpán, J.; Belluzzi, L.; Asensio Ramos, A.; Manso
   Sainz, R.; De Pomtieu, B.; Ichimoto, K.; Carlsson, M.; Casini, R.
Bibcode: 2019ASPC..526..305I
Altcode:
  The Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP; Kano et
  al. 2012; Kobayashi et al. 2012; Kubo et al. 2014) observed, for the
  first time, the linear polarization produced by scattering processes
  in the hydrogen Lyman-α (121.57 nm) and Si III (120.56 nm) lines of
  the solar disk radiation. The complexity of the observed scattering
  polarization (i.e., conspicuous spatial variations in Q/I and U/I
  at spatial scales of 10″-20″ and the absence of center-to- limb
  variation at the Lyman-α center; see Kano et al. 2017) motivated us
  to search for possible hints of the operation of the Hanle effect by
  comparing: (a) the Lyman-α line center signal, for which the critical
  field strength (B<SUB>H</SUB>) for the onset of the Hanle effect is
  53 G, (b) the Lyman-α wing, which is insensitive to the Hanle effect,
  and (c) the Si III line, whose B<SUB>H</SUB> = 290 G. We focus on four
  regions with different total unsigned photospheric magnetic fluxes
  (estimated from SDO/HMI observations), and compare the corresponding
  U/I spatial variations in the Lyman-α wing, Lyman-α center, and Si III
  line. The U/I signal in the Lyman-α wing shows an antisymmetric spatial
  distribution, which is caused by the presence of a bright structure in
  all the selected regions, regardless of the total unsigned photospheric
  magnetic flux. In an internetwork region, the Lyman-α center shows an
  antisymmetric spatial variation across the selected bright structure,
  but it does not show it in other more magnetized regions. In the Si III
  line, the spatial variation of U/I deviates from the above-mentioned
  antisymmetric shape as the total unsigned photospheric magnetic flux
  increases. We argue that a plausible explanation of this differential
  behavior is the operation of the Hanle effect. <P />This work, presented
  in an oral contribution at this Workshop, has been published on The
  Astrophysical Journal (Ishikawa et al. 2017).

Title: CLASP Constraints on the Magnetization and Geometrical
    Complexity of the Chromosphere-Corona Transition Region
Authors: Trujillo Bueno, J.; Štěpán, J.; Belluzzi, L.; Asensio
   Ramos, A.; Manso Sainz, R.; del Pino Alemán, T.; Casini, R.; Ishikawa,
   R.; Kano, R.; Winebarger, A.; Auchère, F.; Narukage, N.; Kobayashi,
   K.; Bando, T.; Katsukawa, Y.; Kubo, M.; Ishikawa, S.; Giono, G.; Hara,
   H.; Suematsu, Y.; Shimizu, T.; Sakao, T.; Tsuneta, S.; Ichimoto, K.;
   Cirtain, J.; Champey, P.; De Pontieu, B.; Carlsson, M.
Bibcode: 2018ApJ...866L..15T
Altcode: 2018arXiv180908865T
  The Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP) is a
  suborbital rocket experiment that on 2015 September 3 measured
  the linear polarization produced by scattering processes in the
  hydrogen Lyα line of the solar disk radiation. The line-center
  photons of this spectral line radiation mostly stem from the
  chromosphere-corona transition region (TR). These unprecedented
  spectropolarimetric observations revealed an interesting surprise,
  namely that there is practically no center-to-limb variation (CLV) in
  the Q/I line-center signals. Using an analytical model, we first show
  that the geometric complexity of the corrugated surface that delineates
  the TR has a crucial impact on the CLV of the Q/I and U/I line-center
  signals. Second, we introduce a statistical description of the solar
  atmosphere based on a 3D model derived from a state-of-the-art radiation
  magnetohydrodynamic simulation. Each realization of the statistical
  ensemble is a 3D model characterized by a given degree of magnetization
  and corrugation of the TR, and for each such realization we solve the
  full 3D radiative transfer problem taking into account the impact
  of the CLASP instrument degradation on the calculated polarization
  signals. Finally, we apply the statistical inference method presented
  in a previous paper to show that the TR of the 3D model that produces
  the best agreement with the CLASP observations has a relatively weak
  magnetic field and a relatively high degree of corrugation. We emphasize
  that a suitable way to validate or refute numerical models of the upper
  solar chromosphere is by confronting calculations and observations
  of the scattering polarization in ultraviolet lines sensitive to the
  Hanle effect.

Title: A Statistical Inference Method for Interpreting the CLASP
    Observations
Authors: Štěpán, J.; Trujillo Bueno, J.; Belluzzi, L.; Asensio
   Ramos, A.; Manso Sainz, R.; del Pino Alemán, T.; Casini, R.; Kano, R.;
   Winebarger, A.; Auchère, F.; Ishikawa, R.; Narukage, N.; Kobayashi,
   K.; Bando, T.; Katsukawa, Y.; Kubo, M.; Ishikawa, S.; Giono, G.; Hara,
   H.; Suematsu, Y.; Shimizu, T.; Sakao, T.; Tsuneta, S.; Ichimoto, K.;
   Cirtain, J.; Champey, P.; De Pontieu, B.; Carlsson, M.
Bibcode: 2018ApJ...865...48S
Altcode: 2018arXiv180802725S
  On 2015 September 3, the Chromospheric Lyman-Alpha SpectroPolarimeter
  (CLASP) successfully measured the linear polarization produced by
  scattering processes in the hydrogen Lyα line of the solar disk
  radiation, revealing conspicuous spatial variations in the Q/I and U/I
  signals. Via the Hanle effect, the line-center Q/I and U/I amplitudes
  encode information on the magnetic field of the chromosphere-corona
  transition region, but they are also sensitive to the three-dimensional
  structure of this corrugated interface region. With the help of a simple
  line-formation model, here we propose a statistical inference method
  for interpreting the Lyα line-center polarization observed by CLASP.

Title: Current State of UV Spectro-Polarimetry and its Future
    Direction
Authors: Ishikawa, Ryohko; Sakao, Taro; Katsukawa, Yukio; Hara,
   Hirohisa; Ichimoto, Kiyoshi; Shimizu, Toshifumi; Kubo, Masahito;
   Auchere, Frederic; De Pontieu, Bart; Winebarger, Amy; Kobayashi,
   . Ken; Kano, Ryouhei; Narukage, Noriyuki; Trujillo Bueno, Javier;
   Song, Dong-uk; Manso Sainz, Rafael; Asensio Ramos, Andres; Leenaarts,
   Jorritt; Carlsson, Mats; Bando, Takamasa; Ishikawa, Shin-nosuke;
   Tsuneta, Saku; Belluzzi, Luca; Suematsu, Yoshinori; Giono, Gabriel;
   Yoshida, Masaki; Goto, Motoshi; Del Pino Aleman, Tanausu; Stepan,
   Jiri; Okamoto, Joten; Tsuzuki, Toshihiro; Uraguchi, Fumihiro; Champey,
   Patrick; Alsina Ballester, Ernest; Casini, Roberto; McKenzie, David;
   Rachmeler, Laurel; Bethge, Christian
Bibcode: 2018cosp...42E1564I
Altcode:
  To obtain quantitative information on the magnetic field in low beta
  regions (i.e., upper chromosphere and above) has been increasingly
  important to understand the energetic phenomena of the outer
  solar atmosphere such as flare, coronal heating, and the solar wind
  acceleration. In the UV range, there are abundant spectral lines that
  originate in the upper chromosphere and transition region. However,
  the Zeeman effect in these spectral lines does not give rise to easily
  measurable polarization signals because of the weak magnetic field
  strength and the larger Doppler broadening compared with the Zeeman
  effect. Instead, the Hanle effect in UV lines is expected to be a
  suitable diagnostic tool of the magnetic field in the upper atmospheric
  layers. To investigate the validity of UV spectro-polarimetry and
  the Hanle effect, the Chromospheric Lyman-Alpha Spectro-Polarimeter
  (CLASP), which is a NASA sounding- rocket experiment, was launched at
  White Sands in US on September 3, 2015. During its 5 minutes ballistic
  flight, it successfully performed spectro-polarimetric observations
  of the hydrogen Lyman-alpha line (121.57 nm) with an unprecedentedly
  high polarization sensitivity of 0.1% in this wavelength range. CLASP
  observed the linear polarization produced by scattering process in VUV
  lines for the first time and detected the polarization signals which
  indicate the operation of the Hanle effect. Following the success
  of CLASP, we are confident that UV spectro-polarimetry is the way
  to proceed, and we are planning the second flight of CLASP (CLASP2:
  Chromospheric LAyer SpectroPolarimeter 2). For this second flight we
  will carry out spectro-polarimetry in the Mg II h and k lines around
  280 nm, with minimum modifications of the CLASP1 instrument. The linear
  polarization in the Mg II k line is induced by scattering processes and
  the Hanle effect, being sensitive to magnetic field strengths of 5 to 50
  G. In addition, the circular polarizations in the Mg II h and k lines
  induced by the Zeeman effect can be measurable in at least plage and
  active regions. The combination of the Hanle and Zeeman effects could
  help us to more reliably infer the magnetic fields of the upper solar
  chromosphere. CLASP2 was selected for flight and is being developed for
  launch in the spring of 2019.Based on these sounding rocket experiments
  (CLASP1 and 2), we aim at establishing the strategy and refining the
  instrument concept for future space missions to explore the enigmatic
  atmospheric layers via UV spectro-polarimetry.

Title: X-Ray Telescope (XRT) Aboard Hinode: Key Instrumental Features
    and Scientific Highlights
Authors: Sakao, Taro
Bibcode: 2018ASSL..449...43S
Altcode:
  No abstract at ADS

Title: White paper of the "soft X-ray imaging spectroscopy"
Authors: Narukage, Noriyuki; Ishikawa, Shin-nosuke; Kawate, Tomoko;
   Imada, Shinsuke; Sakao, Taro
Bibcode: 2017arXiv170604536N
Altcode:
  The solar corona is full of dynamic phenomena, e.g., solar flares,
  micro flares in active regions, jets in coronal holes and in the polar
  regions, X-ray bright points in quiet regions, etc. They are accompanied
  by interesting physical processes, namely, magnetic reconnection,
  particle acceleration, shocks, waves, flows, evaporation, heating,
  cooling, and so on. The understandings of these phenomena and processes
  have been progressing step-by-step with the evolution of the observation
  technology in EUV and X-rays from the space. But, there are fundamental
  questions remain unanswered, or haven't even addressed so far. Our
  scientific objective is to understand underlying physics of dynamic
  phenomena in the solar corona, covering some of the long-standing
  questions in solar physics such as particle acceleration in flares
  and coronal heating. In order to achieve these science objectives,
  we identify the imaging spectroscopy (the observations with spatial,
  temporal and energy resolutions) in the soft X-ray range (from ~0.5
  keV to ~10 keV) is a powerful approach for the detection and analysis
  of energetic events.

Title: Indication of the Hanle Effect by Comparing the Scattering
    Polarization Observed by CLASP in the Lyα and Si III 120.65 nm Lines
Authors: Ishikawa, R.; Trujillo Bueno, J.; Uitenbroek, H.; Kubo, M.;
   Tsuneta, S.; Goto, M.; Kano, R.; Narukage, N.; Bando, T.; Katsukawa,
   Y.; Ishikawa, S.; Giono, G.; Suematsu, Y.; Hara, H.; Shimizu, T.;
   Sakao, T.; Winebarger, A.; Kobayashi, K.; Cirtain, J.; Champey, P.;
   Auchère, F.; Štěpán, J.; Belluzzi, L.; Asensio Ramos, A.; Manso
   Sainz, R.; De Pontieu, B.; Ichimoto, K.; Carlsson, M.; Casini, R.
Bibcode: 2017ApJ...841...31I
Altcode:
  The Chromospheric Lyman-Alpha Spectro-Polarimeter is a sounding
  rocket experiment that has provided the first successful measurement
  of the linear polarization produced by scattering processes in
  the hydrogen Lyα line (121.57 nm) radiation of the solar disk. In
  this paper, we report that the Si III line at 120.65 nm also shows
  scattering polarization and we compare the scattering polarization
  signals observed in the Lyα and Si III lines in order to search for
  observational signatures of the Hanle effect. We focus on four selected
  bright structures and investigate how the U/I spatial variations vary
  between the Lyα wing, the Lyα core, and the Si III line as a function
  of the total unsigned photospheric magnetic flux estimated from Solar
  Dynamics Observatory/Helioseismic and Magnetic Imager observations. In
  an internetwork region, the Lyα core shows an antisymmetric spatial
  variation across the selected bright structure, but it does not show
  it in other more magnetized regions. In the Si III line, the spatial
  variation of U/I deviates from the above-mentioned antisymmetric
  shape as the total unsigned photospheric magnetic flux increases. A
  plausible explanation of this difference is the operation of the Hanle
  effect. We argue that diagnostic techniques based on the scattering
  polarization observed simultaneously in two spectral lines with very
  different sensitivities to the Hanle effect, like Lyα and Si III,
  are of great potential interest for exploring the magnetism of the
  upper solar chromosphere and transition region.

Title: Polarization Calibration of the Chromospheric Lyman-Alpha
    SpectroPolarimeter for a 0.1% Polarization Sensitivity in the VUV
Range. Part II: In-Flight Calibration
Authors: Giono, G.; Ishikawa, R.; Narukage, N.; Kano, R.; Katsukawa,
   Y.; Kubo, M.; Ishikawa, S.; Bando, T.; Hara, H.; Suematsu, Y.;
   Winebarger, A.; Kobayashi, K.; Auchère, F.; Trujillo Bueno, J.;
   Tsuneta, S.; Shimizu, T.; Sakao, T.; Cirtain, J.; Champey, P.; Asensio
   Ramos, A.; Štěpán, J.; Belluzzi, L.; Manso Sainz, R.; De Pontieu,
   B.; Ichimoto, K.; Carlsson, M.; Casini, R.; Goto, M.
Bibcode: 2017SoPh..292...57G
Altcode:
  The Chromospheric Lyman-Alpha SpectroPolarimeter is a sounding
  rocket instrument designed to measure for the first time the linear
  polarization of the hydrogen Lyman-α line (121.6 nm). The instrument
  was successfully launched on 3 September 2015 and observations were
  conducted at the solar disc center and close to the limb during the
  five-minutes flight. In this article, the disc center observations are
  used to provide an in-flight calibration of the instrument spurious
  polarization. The derived in-flight spurious polarization is consistent
  with the spurious polarization levels determined during the pre-flight
  calibration and a statistical analysis of the polarization fluctuations
  from solar origin is conducted to ensure a 0.014% precision on the
  spurious polarization. The combination of the pre-flight and the
  in-flight polarization calibrations provides a complete picture of
  the instrument response matrix, and a proper error transfer method
  is used to confirm the achieved polarization accuracy. As a result,
  the unprecedented 0.1% polarization accuracy of the instrument in the
  vacuum ultraviolet is ensured by the polarization calibration.

Title: Discovery of Scattering Polarization in the Hydrogen Lyα
    Line of the Solar Disk Radiation
Authors: Kano, R.; Trujillo Bueno, J.; Winebarger, A.; Auchère, F.;
   Narukage, N.; Ishikawa, R.; Kobayashi, K.; Bando, T.; Katsukawa, Y.;
   Kubo, M.; Ishikawa, S.; Giono, G.; Hara, H.; Suematsu, Y.; Shimizu,
   T.; Sakao, T.; Tsuneta, S.; Ichimoto, K.; Goto, M.; Belluzzi, L.;
   Štěpán, J.; Asensio Ramos, A.; Manso Sainz, R.; Champey, P.;
   Cirtain, J.; De Pontieu, B.; Casini, R.; Carlsson, M.
Bibcode: 2017ApJ...839L..10K
Altcode: 2017arXiv170403228K
  There is a thin transition region (TR) in the solar atmosphere where
  the temperature rises from 10,000 K in the chromosphere to millions
  of degrees in the corona. Little is known about the mechanisms that
  dominate this enigmatic region other than the magnetic field plays a
  key role. The magnetism of the TR can only be detected by polarimetric
  measurements of a few ultraviolet (UV) spectral lines, the Lyα line
  of neutral hydrogen at 121.6 nm (the strongest line of the solar UV
  spectrum) being of particular interest given its sensitivity to the
  Hanle effect (the magnetic-field-induced modification of the scattering
  line polarization). We report the discovery of linear polarization
  produced by scattering processes in the Lyα line, obtained with
  the Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP) rocket
  experiment. The Stokes profiles observed by CLASP in quiet regions of
  the solar disk show that the Q/I and U/I linear polarization signals are
  of the order of 0.1% in the line core and up to a few percent in the
  nearby wings, and that both have conspicuous spatial variations with
  scales of ∼10 arcsec. These observations help constrain theoretical
  models of the chromosphere-corona TR and extrapolations of the
  magnetic field from photospheric magnetograms. In fact, the observed
  spatial variation from disk to limb of polarization at the line core
  and wings already challenge the predictions from three-dimensional
  magnetohydrodynamical models of the upper solar chromosphere.

Title: Creation of Super-Hot Plasmas in a Flux Eruption Event as
    seen in Soft X-rays with Hinode/XRT
Authors: Sakao, T.; Shimojo, M.; Narukage, N.
Bibcode: 2016AGUFMSH11D..04S
Altcode:
  The X-Ray Telescope (XRT) aboard Hinode observes soft X-ray emission
  from the solar corona with its energy range 0.06 - 2 keV and is capable
  of imaging, and diagnosing, a wide range of coronal temperatures
  from below 1 MK to beyond 20 MK, without gaps in the temperature
  coverage. In particular, the grazing-incidence nature of the XRT
  optics is suited for imaging high-temperature plasmas (&gt;20 MK)
  created during the course of flares that are not necessarily well
  accessible with coronal imagers utilizing EUV emission lines. We
  report XRT observations of an eruptive flare (GOES M1.1) that took
  place behind the east limb at 18:30 UT on 14 October 2014. X-ray
  images traced a flux eruption which corresponds to the early stage of
  a CME observed with SoHO/LASCO, with a flux-rope-like feature ejected
  as the flare progressed. Filter-ratio temperatures of the soft X-ray
  flaring structure derived from multiple-filter observation of the flare
  suggest possible creation of super-hot (reaching as high as 30 MK)
  plasmas that distributed from near the apex of the erupting structure
  (where the flux rope was present), downwards along the sides of the
  structure. The observation may be the first identification in images of
  super-hot plasmas in the soft X-ray range, covering up to 2 keV. XRT
  observations on the creation of super-hot plasmas during the course
  of the flux eruption will be reported and its implication discussed.

Title: Discovery of Ubiquitous Fast-Propagating Intensity Disturbances
    by the Chromospheric Lyman Alpha Spectropolarimeter (CLASP)
Authors: Kubo, M.; Katsukawa, Y.; Suematsu, Y.; Kano, R.; Bando,
   T.; Narukage, N.; Ishikawa, R.; Hara, H.; Giono, G.; Tsuneta, S.;
   Ishikawa, S.; Shimizu, T.; Sakao, T.; Winebarger, A.; Kobayashi, K.;
   Cirtain, J.; Champey, P.; Auchère, F.; Trujillo Bueno, J.; Asensio
   Ramos, A.; Štěpán, J.; Belluzzi, L.; Manso Sainz, R.; De Pontieu,
   B.; Ichimoto, K.; Carlsson, M.; Casini, R.; Goto, M.
Bibcode: 2016ApJ...832..141K
Altcode:
  High-cadence observations by the slit-jaw (SJ) optics system of the
  sounding rocket experiment known as the Chromospheric Lyman Alpha
  Spectropolarimeter (CLASP) reveal ubiquitous intensity disturbances
  that recurrently propagate in either the chromosphere or the transition
  region or both at a speed much higher than the speed of sound. The
  CLASP/SJ instrument provides a time series of two-dimensional images
  taken with broadband filters centered on the Lyα line at a 0.6 s
  cadence. The multiple fast-propagating intensity disturbances appear in
  the quiet Sun and in an active region, and they are clearly detected in
  at least 20 areas in a field of view of 527″ × 527″ during the 5
  minute observing time. The apparent speeds of the intensity disturbances
  range from 150 to 350 km s<SUP>-1</SUP>, and they are comparable
  to the local Alfvén speed in the transition region. The intensity
  disturbances tend to propagate along bright elongated structures away
  from areas with strong photospheric magnetic fields. This suggests
  that the observed fast-propagating intensity disturbances are related
  to the magnetic canopy structures. The maximum distance traveled by
  the intensity disturbances is about 10″, and the widths are a few
  arcseconds, which are almost determined by a pixel size of 1.″03. The
  timescale of each intensity pulse is shorter than 30 s. One possible
  explanation for the fast-propagating intensity disturbances observed
  by CLASP is magnetohydrodynamic fast-mode waves.

Title: Evidence of Electron Acceleration around the Reconnection
    X-point in a Solar Flare
Authors: Narukage, Noriyuki; Shimojo, Masumi; Sakao, Taro
Bibcode: 2016SPD....4730202N
Altcode:
  Particle acceleration is one of the most significant features that
  are ubiquitous among space and cosmic plasmas. It is most prominent
  during flares in the case of the Sun, with which huge amounts of
  electromagnetic radiation and high-energy particles are expelled into
  the interplanetary space through acceleration of plasma particles
  in the corona. Though it has been well understood that energies of
  flares are supplied by the mechanism called magnetic reconnection
  based on the observations in X-rays and EUV with space telescopes,
  where and how in the flaring magnetic field plasmas are accelerated
  has remained unknown due to the low plasma density in the flaring
  corona. We here report the first observational identification of the
  energetic non-thermal electrons around the point of the ongoing magnetic
  reconnection (X-point), with the location of the X-point identified
  by soft X-ray imagery and the localized presence of non-thermal
  electrons identified from imaging-spectroscopic data at two microwave
  frequencies. Considering the existence of the reconnection outflows
  that carries both plasma particles and magnetic fields out from
  the X-point, our identified non-thermal microwave emissions around
  the X-point indicate that the electrons are accelerated around the
  reconnection X-point.

Title: Spectro-polarimetric observation in UV with CLASP to probe
    the chromosphere and transition region
Authors: Kano, Ryouhei; Ishikawa, Ryohko; Winebarger, Amy R.; Auchère,
   Frédéric; Trujillo Bueno, Javier; Narukage, Noriyuki; Kobayashi,
   Ken; Bando, Takamasa; Katsukawa, Yukio; Kubo, Masahito; Ishikawa,
   Shin-Nosuke; Giono, Gabriel; Hara, Hirohisa; Suematsu, Yoshinori;
   Shimizu, Toshifumi; Sakao, Taro; Tsuneta, Saku; Ichimoto, Kiyoshi;
   Goto, Motoshi; Cirtain, Jonathan W.; De Pontieu, Bart; Casini, Roberto;
   Manso Sainz, Rafael; Asensio Ramos, Andres; Stepan, Jiri; Belluzzi,
   Luca; Carlsson, Mats
Bibcode: 2016SPD....4710107K
Altcode:
  The Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP) is a NASA
  sounding-rocket experiment that was performed in White Sands in
  the US on September 3, 2015. During its 5-minute ballistic flight,
  CLASP successfully made the first spectro-polarimetric observation in
  the Lyman-alpha line (121.57 nm) originating in the chromosphere and
  transition region. Since the Lyman-alpha polarization is sensitive
  to magnetic field of 10-100 G by the Hanle effect, we aim to infer
  the magnetic field information in such upper solar atmosphere with
  this experiment.The obtained CLASP data showed that the Lyman-alpha
  scattering polarization is about a few percent in the wings and
  the order of 0.1% in the core near the solar limb, as it had been
  theoretically predicted, and that both polarization signals have a
  conspicuous spatio-temporal variability. CLASP also observed another
  upper-chromospheric line, Si III (120.65 nm), whose critical field
  strength for the Hanle effect is 290 G, and showed a measurable
  scattering polarization of a few % in this line. The polarization
  properties of the Si III line could facilitate the interpretation of
  the scattering polarization observed in the Lyman-alpha line.In this
  presentation, we would like to show how the upper chromosphere and
  transition region are seen in the polarization of these UV lines and
  discuss the possible source of these complicated polarization signals.

Title: Development of precision Wolter mirrors for future solar
    x-ray observations
Authors: Sakao, Taro; Matsuyama, Satoshi; Kime, Ayumi; Goto, Takumi;
   Nishihara, Akihiko; Nakamori, Hiroki; Yamauchi, Kazuto; Kohmura,
   Yoshiki; Miyake, Akira; Hashizume, Hirokazu; Maezawa, Tadakazu;
   Suematsu, Yoshinori; Narukage, Noriyuki
Bibcode: 2015SPIE.9603E..0US
Altcode:
  High resolution imagery of the solar X-ray corona provides a
  crucial key to understand dynamics and heating processes of plasma
  particles there. However, X-ray imagery of the Sun with sub-arcsecond
  resolution has yet to be conducted due to severe technical difficulty in
  fabricating precision Wolter mirrors. For future X-ray observations of
  the Sun's corona, we are attempting to realize precision Wolter mirrors
  with sub-arcsecond resolution by adopting advanced surface polish and
  metrology methods based on nano-technology to sector mirrors which
  consist of a portion of an entire annulus. Following fabrication
  of the first engineering mirror and subsequent evaluation on the
  X-ray focusing performance in 2013, the second engineering mirror
  was made with improvements in both precision polish and metrology
  introduced. Measurement of focusing performance on the second mirror
  at SPring-8 synchrotron facility with 8 keV X-rays has demonstrated
  that the FWHM size of the PSF core reached down to 0.2" while its HPD
  (Half Power Diameter) size remained at ~3" due to the presence of
  small-angle scatter just outside of the core. Also, there was notable
  difference in the focal length between sagittal and meridional focusing
  which could have been caused by an error in the sag in the meridional
  direction of &lt;10 nm in the mirror area. Further improvements to
  overcome these issues have been planned for the next engineering mirror.

Title: CLASP: A UV Spectropolarimeter on a Sounding Rocket for
    Probing theChromosphere-Corona Transition Regio
Authors: Ishikawa, Ryohko; Kano, Ryouhei; Winebarger, Amy; Auchere,
   Frederic; Trujillo Bueno, Javier; Bando, Takamasa; Narukage,
   Noriyuki; Kobayashi, Ken; Katsukawa, Yukio; Kubo, Masahito; Ishikawa,
   Shin-nosuke; Giono, Gabriel; Tsuneta, Saku; Hara, Hirohisa; Suematsu,
   Yoshinori; Shimizu, Toshifumi; Sakao, Taro; Ichimoto, Kiyoshi;
   Cirtain, Jonathan; De Pontieu, Bart; Casini, Roberto; Manso Sainz,
   Rafael; Asensio Ramos, Andres; Stepan, Jiri; Belluzzi, Luca
Bibcode: 2015IAUGA..2254536I
Altcode:
  The wish to understand the energetic phenomena of the outer solar
  atmosphere makes it increasingly important to achieve quantitative
  information on the magnetic field in the chromosphere-corona
  transition region. To this end, we need to measure and model the
  linear polarization produced by scattering processes and the Hanle
  effect in strong UV resonance lines, such as the hydrogen Lyman-alpha
  line. A team consisting of Japan, USA, Spain, France, and Norway has
  been developing a sounding rocket experiment called the Chromospheric
  Lyman-alpha Spectro-Polarimeter (CLASP). The aim is to detect the
  scattering polarization produced by anisotropic radiation pumping in
  the hydrogen Lyman-alpha line (121.6 nm), and via the Hanle effect to
  try to constrain the magnetic field vector in the upper chromosphere
  and transition region. In this talk, we will present an overview
  of our CLASP mission, its scientific objectives, ground tests made,
  and the latest information on the launch planned for the Summer of 2015.

Title: A Sounding Rocket Experiment for the Chromospheric Lyman-Alpha
    Spectro-Polarimeter (CLASP)
Authors: Kubo, M.; Kano, R.; Kobayashi, K.; Bando, T.; Narukage, N.;
   Ishikawa, R.; Tsuneta, S.; Katsukawa, Y.; Ishikawa, S.; Suematsu, Y.;
   Hara, H.; Shimizu, T.; Sakao, T.; Ichimoto, K.; Goto, M.; Holloway,
   T.; Winebarger, A.; Cirtain, J.; De Pontieu, B.; Casini, R.; Auchère,
   F.; Trujillo Bueno, J.; Manso Sainz, R.; Belluzzi, L.; Asensio Ramos,
   A.; Štěpán, J.; Carlsson, M.
Bibcode: 2014ASPC..489..307K
Altcode:
  A sounding-rocket experiment called the Chromospheric Lyman-Alpha
  Spectro-Polarimeter (CLASP) is presently under development to measure
  the linear polarization profiles in the hydrogen Lyman-alpha (Lyα)
  line at 121.567 nm. CLASP is a vacuum-UV (VUV) spectropolarimeter to aim
  for first detection of the linear polarizations caused by scattering
  processes and the Hanle effect in the Lyα line with high accuracy
  (0.1%). This is a fist step for exploration of magnetic fields in
  the upper chromosphere and transition region of the Sun. Accurate
  measurements of the linear polarization signals caused by scattering
  processes and the Hanle effect in strong UV lines like Lyα are
  essential to explore with future solar telescopes the strength
  and structures of the magnetic field in the upper chromosphere and
  transition region of the Sun. The CLASP proposal has been accepted by
  NASA in 2012, and the flight is planned in 2015.

Title: Current progress of optical alignment procedure of CLASP's
    Lyman-alpha polarimetry instrument
Authors: Giono, G.; Ishikawa, R.; Katsukawa, Y.; Bando, T.; Kano, R.;
   Suematsu, Y.; Narukage, N.; Sakao, Taro; Kobayashi, K.; Auchère, F.
Bibcode: 2014SPIE.9144E..3EG
Altcode:
  The Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP) is a
  sounding-rocket instrument currently under development at the
  National Astronomical Observatory of Japan (NAOJ) as a part of an
  international collaboration. CLASP's optics are composed of a Cassegrain
  telescope and a spectro-polarimeter which are designed to achieve an
  unprecedentedly accurate polarization measurement of the Ly-α line
  at 121.6nm emitted from the solar upper-chromosphere and transition
  region. CLASP's first flight is scheduled for August 2015. Reaching
  such accuracy requires a careful alignment of the optical elements
  to optimize the image quality at 121.6 nm. However Ly-α is absorbed
  by air and therefore the optics alignment has to be done under vacuum
  condition which makes any experiment difficult. To bypass this issue,
  we proposed to align the telescope and the spectrograph separately
  in visible light. Hence we present our alignment procedure for both
  telescope and spectro-polarimeter. We will explain details about the
  telescope preliminary alignment before mirrors coating, which was done
  in April 2014, present the telescope combined optical performance
  and compare them to CLASP tolerance. Then we will present details
  about an experiment designed to confirm our alignment procedure for
  the CLASP spectro-polarimeter. We will discuss the resulting image
  quality achieved during this experiment and the lessons learned.

Title: The soft x-ray photon-counting telescope for solar observations
Authors: Sakao, Taro; Narukage, Noriyuki; Suematsu, Yoshinori;
   Watanabe, Kyoko; Shimojo, Masumi; Imada, Shinsuke; Ishikawa,
   Shin-nosuke; DeLuca, Edward E.
Bibcode: 2014SPIE.9144E..3DS
Altcode:
  We present overview and development activities of a soft X-ray
  photon-counting spectroscopic imager for the solar corona that
  we conceive as a possible scientific payload for future space
  solar missions including Japanese Solar-C. The soft X-ray imager
  will employ a Wolter I grazing-incidence sector mirror with which
  images of the corona (1 MK to beyond 10 MK) will be taken with
  the highest-ever angular resolution (0.5"/pixel for a focal length
  of 4 m) as a solar Xray telescope. In addition to high-resolution
  imagery, we attempt to implement photon-counting capability for the
  imager by employing a backside-illuminated CMOS image sensor as the
  focal-plane device. Imaging-spectroscopy of the X-ray corona will be
  performed for the first time in the energy range from ~0.5 keV up to
  10 keV. The imaging-spectroscopic observations with the soft X-ray
  imager will provide a noble probe for investigating mechanism(s) of
  magnetic reconnection and generation of supra-thermal (non-thermal)
  electrons associated with flares. Ongoing development activities in
  Japan towards the photon-counting imager is described with emphasis
  on that for sub-arcsecond-resolution grazing-incidence mirrors.

Title: Evidence of Electron Acceleration around the Reconnection
    X-point in a Solar Flare
Authors: Narukage, Noriyuki; Shimojo, Masumi; Sakao, Taro
Bibcode: 2014ApJ...787..125N
Altcode: 2014arXiv1404.3288N
  Particle acceleration is one of the most significant features that
  are ubiquitous among space and cosmic plasmas. It is most prominent
  during flares in the case of the Sun, with which huge amounts of
  electromagnetic radiation and high-energy particles are expelled into
  the interplanetary space through acceleration of plasma particles
  in the corona. Though it has been well understood that energies of
  flares are supplied by the mechanism called magnetic reconnection
  based on the observations in X-rays and EUV with space telescopes,
  where and how in the flaring magnetic field plasmas are accelerated
  has remained unknown due to the low plasma density in the flaring
  corona. We here report the first observational identification of the
  energetic non-thermal electrons around the point of the ongoing magnetic
  reconnection (X-point), with the location of the X-point identified
  by soft X-ray imagery and the localized presence of non-thermal
  electrons identified from imaging-spectroscopic data at two microwave
  frequencies. Considering the existence of the reconnection outflows
  that carries both plasma particles and magnetic fields out from
  the X-point, our identified non-thermal microwave emissions around
  the X-point indicate that the electrons are accelerated around the
  reconnection X-point. Additionally, the plasma around the X-point was
  also thermally heated up to 10 MK. The estimated reconnection rate of
  this event is ~0.017.

Title: Coronal-Temperature-Diagnostic Capability of the Hinode/ X-Ray
    Telescope Based on Self-consistent Calibration. II. Calibration with
    On-Orbit Data
Authors: Narukage, N.; Sakao, T.; Kano, R.; Shimojo, M.; Winebarger,
   A.; Weber, M.; Reeves, K. K.
Bibcode: 2014SoPh..289.1029N
Altcode: 2013arXiv1307.4489N
  The X-Ray Telescope (XRT) onboard the Hinode satellite is an
  X-ray imager that observes the solar corona with the capability of
  diagnosing coronal temperatures from less than 1 MK to more than
  10 MK. To make full use of this capability, Narukage et al. (Solar
  Phys.269, 169, 2011) determined the thickness of each of the X-ray
  focal-plane analysis filters based on calibration measurements
  from the ground-based end-to-end test. However, in their paper,
  the calibration of the thicker filters for observations of active
  regions and flares, namely the med-Be, med-Al, thick-Al and thick-Be
  filters, was insufficient due to the insufficient X-ray flux used in
  the measurements. In this work, we recalibrate those thicker filters
  using quiescent active region data taken with multiple filters of
  XRT. On the basis of our updated calibration results, we present the
  revised coronal-temperature-diagnostic capability of XRT.

Title: Chromospheric Lyman Alpha SpectroPolarimeter: CLASP
Authors: Kobayashi, Ken; Kano, R.; Trujillo Bueno, J.; Winebarger,
   A. R.; Cirtain, J. W.; Bando, T.; De Pontieu, B.; Ishikawa, R.;
   Katsukawa, Y.; Kubo, M.; Narukage, N.; Sakao, T.; Tsuneta, S.;
   Auchère, F.; Asensio Ramos, A.; Belluzzi, L.; Carlsson, M.; Casini,
   R.; Hara, H.; Ichimoto, K.; Manso Sainz, R.; Shimizu, T.; Stepan,
   J.; Suematsu, Y.; Holloway, T.
Bibcode: 2013SPD....44..142K
Altcode:
  The Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP) is a VUV
  spectropolarimeter optimized for measuring the linear polarization of
  the Lyman-alpha line (121.6 nm). The Lyman-alpha line is predicted to
  show linear polarization caused by atomic scattering in the chromosphere
  and modified by the magnetic field through the Hanle effect. The
  Hanle effect is sensitive to weaker magnetic fields than Zeeman
  effect, and is not canceled by opposing fields, making it sensitive
  to tangled or unresolved magnetic field structures. These factors make
  the Hanle effect a valuable tool for probing the magnetic field in the
  chromosphere above the quiet sun. To meet this goal, CLASP is designed
  to measure linear polarization with 0.1% polarization sensitivity
  at 0.01 nm spectral resolution and 10" spatial resolution. CLASP is
  scheduled to be launched in 2015.

Title: Next space solar observatory SOLAR-C: mission instruments
    and science objectives
Authors: Katsukawa, Y.; Watanabe, T.; Hara, H.; Ichimoto, K.; Kubo,
   M.; Kusano, K.; Sakao, T.; Shimizu, T.; Suematsu, Y.; Tsuneta, S.
Bibcode: 2012IAUSS...6E.207K
Altcode:
  SOLAR-C, the fourth space solar mission in Japan, is under study with a
  launch target of fiscal year 2018. A key concept of the mission is to
  view the photosphere, chromosphere, and corona as one system coupled
  by magnetic fields along with resolving the size scale of fundamental
  physical processes connecting these atmospheric layers. It is especially
  important to study magnetic structure in the chromosphere as an
  interface layer between the photosphere and the corona. The SOLAR-C
  satellite is equipped with three telescopes, the Solar UV-Visible-IR
  Telescope (SUVIT), the EUV/FUV High Throughput Spectroscopic Telescope
  (EUVS/LEMUR), and the X-ray Imaging Telescope (XIT). Observations
  with SUVIT of photospheric and chromospheric magnetic fields make it
  possible to infer three dimensional magnetic structure extending from
  the photosphere to the chromosphere and corona.This helps to identify
  magnetic structures causing magnetic reconnection, and clarify how
  waves are propagated, reflected, and dissipated. Phenomena indicative
  of or byproducts of magnetic reconnection, such as flows and shocks,
  are to be captured by SUVIT and by spectroscopic observations using
  EUVS/LEMUR, while XIT observes rapid changes in temperature distribution
  of plasma heated by shock waves.

Title: Hinode observations of the Venus corona during the 2012
    transit of Venus
Authors: Kanao, M.; Yamazaki, A.; Imada, S.; Shimizu, T.; Sakao, T.;
   Kasaba, Y.; Sakanoi, T.; Kagitani, M.; Nakamura, M.
Bibcode: 2012AGUFM.P11D1851K
Altcode:
  The Hinode satellite successfully observed the transit of Venus on
  5th June 2012 with the highest spatial resolution. This presentation
  will focus on UV and soft X-ray data acquired with the EUV Imaging
  Spectrometer (EIS) and the X-ray Telescope (XRT) onboard Hinode. We
  expected the EUV and X-ray emissions from the charge exchange reaction
  by the solar wind impacting on the neutral particles in Venus upper
  atmosphere. The neutral particles escape through the photoreaction, the
  solar wind pick-up process, and so on, in connection with the solar wind
  and the solar radiation. However, there are few precedent observations
  of the escaping hydrogen and oxygen, ranging from a few eV to a few keV
  because of difficulty in the groundbased observations. The atmosphere
  loss can be estimated based on the two-dimensional image of the neutral
  particle density. Our estimation was made for 18.4nm (OVI), 19.3nm (OV)
  and 25.6nm (HII), which intensity and line profiles can be recorded with
  EIS, and 1.72-2.18nm (OVII), 1.60-1.90nm(OVIII), 2.85-3.37nm (CVI),
  3.50-4.03 nm (CV), which are located in XRT's broadband range. Multi
  wavelength observation could clarify the collision velocities between
  the solar wind and Venus neutral particles. Before the transit of Venus,
  for science planning purpose, we estimated the EUV and X-ray emission
  intensities by using typical solar wind parameters (the proton density
  10/cc and the solar wind velocity 400 km/sec) with a Venus atmosphere
  model. The photon production rate of the X-ray emission is estimated
  to be 1.1 x 10^25 photons/s, and that of the OVI emission line (18.4nm)
  is 6.9 x 10^23 photons/s. These values are much lower than the emissions
  from the solar corona, but unexpected signals may be observed dureing
  the transit. In this presentation, we will present the calculation
  results on intensity distribution of the Venus corona and some X-ray
  and EUV data acquired during the transit. Also we briefly compare
  the observed intensities in dark Venus feature with the calculation
  results and discuss the signification of the difference.

Title: Chromospheric Lyman-alpha spectro-polarimeter (CLASP)
Authors: Kano, Ryouhei; Bando, Takamasa; Narukage, Noriyuki; Ishikawa,
   Ryoko; Tsuneta, Saku; Katsukawa, Yukio; Kubo, Masahito; Ishikawa,
   Shin-nosuke; Hara, Hirohisa; Shimizu, Toshifumi; Suematsu, Yoshinori;
   Ichimoto, Kiyoshi; Sakao, Taro; Goto, Motoshi; Kato, Yoshiaki; Imada,
   Shinsuke; Kobayashi, Ken; Holloway, Todd; Winebarger, Amy; Cirtain,
   Jonathan; De Pontieu, Bart; Casini, Roberto; Trujillo Bueno, Javier;
   Štepán, Jiří; Manso Sainz, Rafael; Belluzzi, Luca; Asensio Ramos,
   Andres; Auchère, Frédéric; Carlsson, Mats
Bibcode: 2012SPIE.8443E..4FK
Altcode:
  One of the biggest challenges in heliophysics is to decipher the
  magnetic structure of the solar chromosphere. The importance of
  measuring the chromospheric magnetic field is due to both the key role
  the chromosphere plays in energizing and structuring the outer solar
  atmosphere and the inability of extrapolation of photospheric fields to
  adequately describe this key boundary region. Over the last few years,
  significant progress has been made in the spectral line formation
  of UV lines as well as the MHD modeling of the solar atmosphere. It
  is found that the Hanle effect in the Lyman-alpha line (121.567 nm)
  is a most promising diagnostic tool for weaker magnetic fields in
  the chromosphere and transition region. Based on this groundbreaking
  research, we propose the Chromospheric Lyman-Alpha Spectro-Polarimeter
  (CLASP) to NASA as a sounding rocket experiment, for making the first
  measurement of the linear polarization produced by scattering processes
  and the Hanle effect in the Lyman-alpha line (121.567 nm), and making
  the first exploration of the magnetic field in the upper chromosphere
  and transition region of the Sun. The CLASP instrument consists
  of a Cassegrain telescope, a rotating 1/2-wave plate, a dual-beam
  spectrograph assembly with a grating working as a beam splitter, and
  an identical pair of reflective polarization analyzers each equipped
  with a CCD camera. We propose to launch CLASP in December 2014.

Title: The x-ray/EUV telescope for the Solar-C mission: science and
    development activities
Authors: Sakao, Taro; Narukage, Noriyuki; Imada, Shinsuke; Suematsu,
   Yoshinori; Shimojo, Masumi; Tsuneta, Saku; DeLuca, Edward E.; Watanabe,
   Kyoko; Ishikawa, Shin-nosuke
Bibcode: 2012SPIE.8443E..0AS
Altcode:
  We report science and development activities of the X-ray/EUV telescope
  for the Japanese Solar-C mission whose projected launch around 2019. The
  telescope consists of a package of (a) a normal-incidence (NI) EUV
  telescope and (b) a grazing-incidence (GI) soft X-ray telescope. The NI
  telescope chiefly provides images of low corona (whose temperature 1
  MK or even lower) with ultra-high angular resolution (0.2-0.3"/pixel)
  in 3 wavelength bands (304, 171, and 94 angstroms). On the other
  hand, the GI telescope provides images of the corona with a wide
  temperature coverage (1 MK to beyond 10 MK) with the highest-ever
  angular resolution (~0.5"/pixel) as a soft X-ray coronal imager. The
  set of NI and GI telescopes should provide crucial information for
  establishing magnetic and gas-dynamic connection between the corona and
  the lower atmosphere of the Sun which is essential for understanding
  heating of, and plasma activities in, the corona. Moreover, we attempt
  to implement photon-counting capability for the GI telescope with
  which imaging-spectroscopy of the X-ray corona will be performed for
  the first time, in the energy range from ~0.5 keV up to 10 keV. The
  imaging-spectroscopic observations will provide totally-new information
  on mechanism(s) for the generation of hot coronal plasmas (heated
  beyond a few MK), those for magnetic reconnection, and even generation
  of supra-thermal electrons associated with flares. An overview of
  instrument outline and science for the X-ray photoncounting telescope
  are presented, together with ongoing development activities in Japan
  towards soft X-ray photoncounting observations, focusing on high-speed
  X-ray CMOS detector and sub-arcsecond-resolution GI mirror.

Title: The SOLAR-C Mission: Plan B Payload Concept
Authors: Shimizu, T.; Sakao, T.; Katsukawa, Y.; Group, J. S. W.
Bibcode: 2012ASPC..454..449S
Altcode:
  The telescope concepts for the SOLAR-C Plan B mission as of the time of
  the Hinode-3 meeting were briefly presented for having comments from
  the international solar physics community. The telescope candidates
  are 1) near IR-visible-UV telescope with 1.5m aperture and enhanced
  spectro-polarimetric capability, 2) UV/EUV high throughput spectrometer,
  and 3) next generation X-ray telescope.

Title: X-ray performance of 0.18 µm CMOS APS test arrays for solar
    observation
Authors: Dryer, B. J.; Holland, A. D.; Jerram, P.; Sakao, Taro
Bibcode: 2012SPIE.8453E..2JD
Altcode:
  Solar-C is the third generation solar observatory led by JAXA. The
  accepted ‘Plan-B’ payload calls for a radiation-hard solar-staring
  photon-counting x-ray spectrometer. CMOS APS technology offers
  advantages over CCDs for such an application such as increased radiation
  hardness and high frame rate (instrument target of 1000 fps). Looking
  towards the solution of a bespoke CMOS APS, this paper reports the
  x-ray spectroscopy performance, concentrating on charge collection
  efficiency and split event analysis, of two baseline e2v CMOS APSs
  not designed for x-ray performance, the EV76C454 and the Ocean Colour
  Imager (OCI) test array. The EV76C454 is an industrial 5T APS designed
  for machine vision, available back and front illuminated. The OCI test
  arrays have varying pixel design across the chips, but are 4T, back
  illuminated and have thin low-resistivity and thick high-resistivity
  variants. The OCI test arrays’ pixel variants allow understanding
  of how pixel design can affect x-ray performance.

Title: The Chromospheric Lyman-Alpha SpectroPolarimeter: CLASP
Authors: Kobayashi, K.; Kano, R.; Trujillo-Bueno, J.; Asensio Ramos,
   A.; Bando, T.; Belluzzi, L.; Carlsson, M.; De Pontieu, R. C. B.; Hara,
   H.; Ichimoto, K.; Ishikawa, R.; Katsukawa, Y.; Kubo, M.; Manso Sainz,
   R.; Narukage, N.; Sakao, T.; Stepan, J.; Suematsu, Y.; Tsuneta, S.;
   Watanabe, H.; Winebarger, A.
Bibcode: 2012ASPC..456..233K
Altcode:
  The magnetic field plays a crucial role in the chromosphere and the
  transition region, and our poor empirical knowledge of the magnetic
  field in the upper chromosphere and transition region is a major
  impediment to advancing the understanding of the solar atmosphere. The
  Hanle effect promises to be a valuable alternative to Zeeman effect
  as a method of measuring the magnetic field in the chromosphere and
  transition region; it is sensitive to weaker magnetic fields, and
  also sensitive to tangled, unresolved field structures. <P />CLASP
  is a sounding rocket experiment that aims to observe the Hanle effect
  polarization of the Lyman α (1215.67Å) line in the solar chromosphere
  and transition region, and prove the usefulness of this technique in
  placing constraints on the magnetic field strength and orientation
  in the low plasma-β region of the solar atmosphere. The Ly-α line
  has been chosen because it is a chromospheric/transition-region line,
  and because the Hanle effect polarization of this line is predicted to
  be sensitive to 10-250 Gauss, encompassing the range of interest. The
  CLASP instrument is designed to measure linear polarization in the
  Ly-α line with a polarization sensitivity of 0.1%. The instrument is
  currently funded for development. The optical design of the instrument
  has been finalized, and an extensive series of component-level tests
  are underway to validate the design.

Title: The Chromospheric Lyman-Alpha SpectroPolarimeter (CLASP)j
Authors: Kobayashi, K.; Tsuneta, S.; Trujillo Bueno, J.; Bando, T.;
   Belluzzi, L.; Casini, R.; Carlsson, M.; Cirtain, J. W.; De Pontieu,
   B.; Hara, H.; Ichimoto, K.; Ishikawa, R.; Kano, R.; Katsukawa, Y.;
   Kim, T.; Kubo, M.; Manso Sainz, R.; Narukage, N.; Asensio Ramos,
   A.; Robinson, B.; Sakao, T.; Shimizu, T.; Stepan, J.; Suematsu, Y.;
   Watanabe, H.; West, E.; Winebarger, A. R.
Bibcode: 2011AGUFM.P14C..05K
Altcode:
  We present an overview of the Chromospheric Lyman-Alpha
  SpectroPolarimeter (CLASP) program. CLASP is a proposed sounding rocket
  experiment currently under development as collaboration between Japan,
  USA and Spain. The aim is to achieve the first measurement of magnetic
  field in the upper chromosphere and transition region of the Sun
  through the detection and measurement of Hanle effect polarization
  of the Lyman alpha line. The Hanle effect (i.e. the magnetic field
  induced modification of the linear polarization due to scattering
  processes in spectral lines) is believed to be a powerful tool for
  measuring the magnetic field in the upper chromosphere, as it is more
  sensitive to weaker magnetic fields than the Zeeman effect, and also
  sensitive to magnetic fields tangled at spatial scales too small to be
  resolved. The Lyman-alpha (121.567 nm) line has been chosen because
  it is a chromospheric/transition-region line, and because the Hanle
  effect polarization of the Lyman-alpha line is predicted to be sensitive
  to 10-250 Gauss, encompassing the range of interest. Hanle effect is
  predicted to be observable as linear polarization or depolarization,
  depending on the geometry, with a fractional polarization amplitude
  varying between 0.1% and 1% depending on the strength and orientation of
  the magnetic field. This quantification of the chromospheric magnetic
  field requires a highly sensitive polarization measurement. The
  CLASP instrument consists of a large aperture (287 mm) Cassegrain
  telescope mated to a polarizing beamsplitter and a matched pair
  of grating spectrographs. The polarizing beamsplitter consists
  of a continuously rotating waveplate and a linear beamsplitter,
  allowing simultaneous measurement of orthogonal polarizations and
  in-flight self-calibration. Development of the instrument is underway,
  and prototypes of all optical components have been tested using a
  synchrotron beamline. The experiment is proposed for flight in 2014.

Title: Photon-counting soft x-ray telescope for the Solar-C mission
Authors: Sakao, Taro; Narukage, Noriyuki; Shimojo, Masumi; Tsuneta,
   Saku; Suematsu, Yoshinori; Miyazaki, Satoshi; Imada, Shinsuke;
   Nishizuka, Naoto; Watanabe, Kyoko; Dotani, Tadayasu; DeLuca, Edward
   E.; Ishikawa, Shin-nosuke
Bibcode: 2011SPIE.8148E..0CS
Altcode: 2011SPIE.8148E..11S
  We report instrument outline as well as science of the photon-counting
  soft X-ray telescope that we have been studying as a possible scientific
  payload for the Japanese Solar-C mission whose projected launch around
  2019. Soft X-rays (~1- 10 keV) from the solar corona include rich
  information on (1) possible mechanism(s) for heating the bright core of
  active regions seen in soft X-rays (namely, the hottest portion in the
  non-flaring corona), (2) dynamics and magnetohydrodynamic structures
  associated with magnetic reconnection processes ongoing in flares,
  and even (3) generation of supra-thermal distributions of coronal
  plasmas associated with flares. Nevertheless, imaging-spectroscopic
  investigation of the soft X-ray corona has so far remained unexplored
  due to difficulty in the instrumentation for achieving this aim. With
  the advent of recent remarkable progress in CMOS-APS detector
  technology, the photon-counting X-ray telescope will be capable
  of, in addition to conventional photon-integration type exposures,
  performing imaging-spectroscopic investigation on active regions and
  flares, thus providing, for example, detailed temperature information
  (beyond the sofar- utilized filter-ratio temperature) at each spatial
  point of the observing target. The photon-counting X-ray telescope will
  emply a Wolter type I optics with a piece of a segmented mirror whose
  focal length 4 meters, combined with a focal-plane CMOS-APS detector
  (0.4-0.5"/pixel) whose frame read-out rate required to be as high as
  1000 fps.

Title: Overview of Chromospheric Lyman-Alpha SpectroPolarimeter
    (CLASP)
Authors: Narukage, Noriyuki; Tsuneta, Saku; Bando, Takamasa; Kano,
   Ryouhei; Kubo, Masahito; Ishikawa, Ryoko; Hara, Hirohisa; Suematsu,
   Yoshinori; Katsukawa, Yukio; Watanabe, Hiroko; Ichimoto, Kiyoshi;
   Sakao, Taro; Shimizu, Toshifumi; Kobayashi, Ken; Robinson, Brian; Kim,
   Tony; Winebarger, Amy; West, Edward; Cirtain, Jonathan; De Pontieu,
   Bart; Casini, Roberto; Trujillo Bueno, Javier; Stepan, Jiri; Manso
   Sainz, Rafael; Belluzzi, Luca; Asensio Ramos, Andres; Carlsson, Mats
Bibcode: 2011SPIE.8148E..0HN
Altcode: 2011SPIE.8148E..16N
  The solar chromosphere is an important boundary, through which all of
  the plasma, magnetic fields and energy in the corona and solar wind
  are supplied. Since the Zeeman splitting is typically smaller than
  the Doppler line broadening in the chromosphere and transition region,
  it is not effective to explore weak magnetic fields. However, this is
  not the case for the Hanle effect, when we have an instrument with
  high polarization sensitivity (~ 0.1%). "Chromospheric Lyman- Alpha
  SpectroPolarimeter (CLASP)" is the sounding rocket experiment to detect
  linear polarization produced by the Hanle effect in Lyman-alpha line
  (121.567 nm) and to make the first direct measurement of magnetic
  fields in the upper chromosphere and lower transition region. To
  achieve the high sensitivity of ~ 0.1% within a rocket flight (5
  minutes) in Lyman-alpha line, which is easily absorbed by materials,
  we design the optical system mainly with reflections. The CLASP
  consists of a classical Cassegrain telescope, a polarimeter and a
  spectrometer. The polarimeter consists of a rotating 1/2-wave plate
  and two reflecting polarization analyzers. One of the analyzer also
  works as a polarization beam splitter to give us two orthogonal linear
  polarizations simultaneously. The CLASP is planned to be launched in
  2014 summer.

Title: The SOLAR-C mission: current status
Authors: Shimizu, Toshifumi; Tsuneta, Saku; Hara, Hirohisa; Ichimoto,
   Kiyoshi; Kusano, Kanya; Sakao, Taro; Sekii, Takashi; Suematsu,
   Yoshinori; Watanabe, Tetsuya
Bibcode: 2011SPIE.8148E..0BS
Altcode: 2011SPIE.8148E..10S
  Two mission concepts (plan A: out-of-ecliptic mission and plan B:
  high resolution spectroscopic mission) have been studied for the next
  Japanese-led solar mission Solar-C, which will follow the scientific
  success of the Hinode mission. The both mission concepts are concluded
  as equally important and attractive for the promotion of space solar
  physics. In the meantime we also had to make efforts for prioritizing
  the two options, in order to proceed to next stage of requesting the
  launch of Solar-C mission at the earliest opportunity. This paper
  briefly describes the two mission concepts and the current status
  on our efforts for prioritizing the two options. More details are
  also described for the plan B option as the first-priority Solar-C
  mission. The latest report from the Solar-C mission concept studies
  was documented as "Interim Report on the Solar-C Mission Concept."

Title: Coronal-Temperature-Diagnostic Capability of the Hinode/
    X-Ray Telescope Based on Self-Consistent Calibration
Authors: Narukage, N.; Sakao, T.; Kano, R.; Hara, H.; Shimojo, M.;
   Bando, T.; Urayama, F.; DeLuca, E.; Golub, L.; Weber, M.; Grigis,
   P.; Cirtain, J.; Tsuneta, S.
Bibcode: 2011SoPh..269..169N
Altcode: 2010arXiv1011.2867N; 2011SoPh..tmp....1N
  The X-Ray Telescope (XRT) onboard the Hinode satellite is an X-ray
  imager that observes the solar corona with unprecedentedly high angular
  resolution (consistent with its 1″ pixel size). XRT has nine X-ray
  analysis filters with different temperature responses. One of the most
  significant scientific features of this telescope is its capability
  of diagnosing coronal temperatures from less than 1 MK to more than
  10 MK, which has never been accomplished before. To make full use
  of this capability, accurate calibration of the coronal temperature
  response of XRT is indispensable and is presented in this article. The
  effect of on-orbit contamination is also taken into account in the
  calibration. On the basis of our calibration results, we review the
  coronal-temperature-diagnostic capability of XRT.

Title: The Chromospheric Lyman Alpha SpectroPolarimeter (CLASP)
Authors: Kobayashi, K.; Tsuneta, S.; Trujillo Bueno, J.; Cirtain,
   J. W.; Bando, T.; Kano, R.; Hara, H.; Fujimura, D.; Ueda, K.; Ishikawa,
   R.; Watanabe, H.; Ichimoto, K.; Sakao, T.; de Pontieu, B.; Carlsson,
   M.; Casini, R.
Bibcode: 2010AGUFMSH11B1632K
Altcode:
  Magnetic fields in the solar chromosphere play a key role in the
  energy transfer and dynamics of the solar atmosphere. Yet a direct
  observation of the chromospheric magnetic field remains one of the
  greatest challenges in solar physics. While some advances have been
  made for observing the Zeeman effect in strong chromospheric lines,
  the effect is small and difficult to detect outside sunspots. The
  Hanle effect offers a promising alternative; it is sensitive to weaker
  magnetic fields (e.g., 5-500 G for Ly-Alpha), and while its magnitude
  saturates at stronger magnetic fields, the linear polarization signals
  remain sensitive to the magnetic field orientation. The Hanle effect
  is not only limited to off-limb observations. Because the chromosphere
  is illuminated by an anisotropic radiation field, the Ly-Alpha line is
  predicted to show linear polarization for on-disk, near-limb regions,
  and magnetic field is predicted to cause a measurable depolarization. At
  disk center, the Ly-Alpha radiation is predicted to be negligible
  in the absence of magnetic field, and linearly polarized to an order
  of 0.3% in the presence of an inclined magnetic field. The proposed
  CLASP sounding rocket instrument is designed to detect 0.3% linear
  polarization of the Ly-Alpha line at 1.5 arcsecond spatial resolution
  (0.7’’ pixel size) and 10 pm spectral resolution. The instrument
  consists of a 30 cm aperture Cassegrain telescope and a dual-beam
  spectropolarimeter. The telescope employs a ``cold mirror’’ design
  that uses multilayer coatings to reflect only the target wavelength
  range into the spectropolarimeter. The polarization analyzer consists of
  a rotating waveplate and a polarizing beamsplitter that comprises MgF2
  plates placed at Brewster’s Angle. Each output beam of the polarizing
  beamsplitter, representing two orthogonal linear polarizations, is
  dispersed and focused using a separate spherical varied-line-space
  grating, and imaged with a separate 512x512 CCD camera. Prototypes
  of key optical components have been fabricated and tested. Instrument
  design is being finalized, and the experiment will be proposed for a
  2014 flight aboard a NASA sounding rocket.

Title: A New View of the Sun with Hinode Mission
Authors: Sakao, Taro; Tsuneta, Saku; Shimojo, Masumi; Narukage,
   Noriyuki; Kano, Ryouhei; Obara, Takahiro; Watari, Shinichi; Hinode Team
Bibcode: 2009TrSpT...7Tr215S
Altcode:
  We present highlights of observations of the Sun with Japanese Hinode
  mission launched by JAXA in September 2006. The scientific objective
  of Hinode mission is to observe, in an unprecedented detail, a wide
  variety of plasma activities in the Sun's corona together with magnetic
  activities on the photosphere and in the chromosphere, utilizing a suite
  of three state-of-the-art telescopes; Solar Optical Telescope (SOT),
  X-Ray Telescope (XRT), and EUV Imaging Spectrometer (EIS). Since the
  beginning of the observations late in October 2006, Hinode has been
  providing ample information on activities of magnetized plasmas in the
  solar atmosphere some of which are totally new to us. In this article,
  we present an overview of the Hinode mission as well as some highlights
  of the observations.

Title: Plasma Outflows in the Corona as Observed With Hinode XRT
Authors: Sakao, T.; Kano, R.; Narukage, N.; Deluca, E. E.; Grigis, P.
Bibcode: 2008AGUFMSH41B1624S
Altcode:
  We present imaging observations of plasma outflows in the solar corona
  made with X-Ray Telescope (XRT) aboard Hinode satellite. The XRT employs
  a back-illuminated CCD as the focal-plane imaging device which enables
  us, together with an optimized set of analysis filters, to investigate,
  for the first time, dynamic behavior of relatively cool (1-2 MK, say)
  plasmas in the corona. The XRT revealed a clear pattern of continuous
  outflow of plasmas from the edge of an active region NOAA AR 10942 right
  adjacent to a coronal hole. Plasmas of temperature ~1 MK flowed out
  with a sub-sonic velocity of typically ~140 km/s along magnetic field
  lines that are most likely open towards the interplanetary space. These
  outflowing plasmas may constitute a fraction of the (slow) solar
  wind. In addition to this discovery, the XRT has so far identified
  rich patterns of continuous outflows including those from coronal
  hole boundaries and along fan-like field lines rooted inside coronal
  holes. XRT observations of such plasma outflows in the corona are
  presented and their possible implications to the solar wind discussed.

Title: The Thermal Structures of Solar Corona Revealed with Hinode/XRT
Authors: Narukage, N.; Sakao, T.; Kano, R.
Bibcode: 2008AGUFMSH52A..03N
Altcode:
  The solar corona has a wide temperature range from less than 1MK
  (1,000,000K) to more than 10MK. The X-ray telescope (XRT) on board
  the Hinode satellite has 9 X-ray analysis filters with different
  temperature responses making it possible to detect both cool and
  hot coronal plasmas. Using the data observed with this telescope,
  we successfully derived the coronal temperature and emission measure
  around the whole sun, i.e., for not only active regions but also quiet
  regions and coronal holes. We also found that coronal structures are
  nicely classified using the temperature and emission measure. And the
  coronal structures were found to depend on the length of structure
  and the heating flux. Furthermore, we calculated the coronal potential
  magnetic field using the photospheric magnetic field. To compare the
  heating flux estimated with coronal temperature and the calculated
  coronal magnetic field might be the great clue to solving the big
  coronal heating question: why does the hot 1MK corona stably exist
  above the cool 6,000K solar surface? In this talk, we will show some
  results of our latest studies about the coronal thermal structures.

Title: Strongly Blueshifted Phenomena Observed with Hinode EIS in
    the 2006 December 13 Solar Flare
Authors: Asai, Ayumi; Hara, Hirohisa; Watanabe, Tetsuya; Imada,
   Shinsuke; Sakao, Taro; Narukage, Noriyuki; Culhane, J. L.; Doschek,
   G. A.
Bibcode: 2008ApJ...685..622A
Altcode: 2008arXiv0805.4468A
  We present a detailed examination of strongly blueshifted emission
  lines observed with the EUV Imaging Spectrometer on board the Hinode
  satellite. We found two kinds of blueshifted phenomenon associated
  with the X3.4 flare that occurred on 2006 December 13. One was related
  to a plasmoid ejection seen in soft X-rays. It was very bright in all
  the lines used for the observations. The other was associated with the
  faint arc-shaped ejection seen in soft X-rays. The soft X-ray ejection
  is thought to be a magnetohydrodynamic (MHD) fast-mode shock wave. This
  is therefore the first spectroscopic observation of an MHD fast-mode
  shock wave associated with a flare.

Title: Source Region of the Solar Wind Identified with Hinode X-Ray
    Telescope
Authors: Sakao, Taro
Bibcode: 2008AstHe.101..491S
Altcode:
  A possible source region for the slow solar wind was identified with
  the X-Ray Telescope aboard Hinode satellite. Continuous outflow of
  hot (~ 1 MK) plasmas was found to emanate from the edge of a solar
  active region adjacent to a coronal hole. Magnetic field lines along
  which outflowing plasmas propagate are most likely opened toward the
  interplanetary space. Hence the observed outflow would constitute a
  part of the solar wind.

Title: Hinode/XRT Diagnostics of Loop Thermal Structure
Authors: Reale, F.; Parenti, S.; Reeves, K. K.; Weber, M.; Bobra,
   M. G.; Barbera, M.; Kano, R.; Narukage, N.; Shimojo, M.; Sakao, T.;
   Peres, G.; Golub, L.
Bibcode: 2008ASPC..397...50R
Altcode:
  We investigate possible diagnostics of the thermal structure of coronal
  loops from Hinode/XRT observations made with several filters. We
  consider the observation of an active region with five filters. We
  study various possible combinations of filter data to optimize for
  sensitivity to thermal structure and for signal enhancement.

Title: Japanese Next Solar Mission: SOLAR-C
Authors: Sakao, T.; Solar-C, W. G.
Bibcode: 2008ESPM...12..6.5S
Altcode:
  We present introductory overview on the next Japanese solar mission,
  SOLAR-C, which has been envisaged following the success of Hinode
  (SOLAR-B) mission. Two plans, Plan A and Plan B, are under extensive
  study from science objectives as well as engineering point of view. Plan
  A aims to perform out-of-ecliptic observations for investigating,
  with helioseismic approach, internal structure and dynamo mechanisms
  of the Sun. It also explores polar regions where fast solar wind is
  believed to be originated. The baseline orbit for Plan A is a circular
  orbit of 1 AU distance from the Sun, with its inclination at around,
  or greater than, 40 degrees. Plan B pursues small-scale plasma processes
  and structures in the solar atmosphere which attract growing interest,
  following Hinode discoveries, for understanding fully dynamism and
  magnetic nature of the atmosphere. With Plan B, high-angular-resolution
  investigation of the entire solar atmosphere (from the photosphere
  to the corona, including their interface layers, i.e., chromosphere
  and transition region) is to be performed with enhanced spectroscopic
  and spectro-polarimetric capability as compared with Hinode, together
  with enhanced sensitivity towards ultra-violet wavelengths. There
  has been wide and evolving support for the SOLAR-C mission not only
  from solar physics community but also from related research areas in
  Japan. We request SOLAR-C to be launched in mid. 2010s. <P />Following
  the highly-successful achievements of international collaboration for
  Yohkoh and Hinode, we strongly hope the SOLAR-C mission be realized
  under extensive collaboration with European and U.S. partners. Japanese
  SOLAR-C working group was officially approved by ISAS/JAXA in December
  2007 for mission studies and promoting international collaboration. It
  is expected that a single mission plan is to be proposed after one
  year of investigation on Plan A and Plan B.

Title: Vertical Temperature Structures of the Solar Corona Derived
    with the Hinode X-Ray Telescope
Authors: Kano, Ryouhei; Sakao, Taro; Narukage, Noriyuki; Tsuneta,
   Saku; Kotoku, Jun'ichi; Bando, Takamasa; Deluca, Edward; Lundquist,
   Loraine; Golub, Leon; Hara, Hirohisa; Matsuzaki, Keiichi; Shimojo,
   Masumi; Shibasaki, Kiyoto; Shimizu, Toshifumi; Nakatani, Ichiro
Bibcode: 2008PASJ...60..827K
Altcode:
  We obtained temperature structures in faint coronal features
  above and near the solar limb with the X-Ray Telescope aboard the
  Hinode satellite by accurately correcting the scattered X-rays
  from surrounding bright regions with occulted images during
  the solar eclipses. Our analysis yields a polar coronal hole
  temperature of about 1.0MK and an emission measure in the range of
  10<SUP>25.5</SUP>-10<SUP>26.0</SUP>cm<SUP>-5</SUP>. In addition,
  our methods allow us to measure the temperature and emission
  measure of two distinct quiet-Sun structures: radial (plume-like)
  structures near the boundary of the coronal-hole and diffuse quiet
  Sun regions at mid-latitudes. The radial structures appear to have
  increasing temperature with height during the first 100Mm, and
  constant temperatures above 100Mm. For the diffuse quiet-Sun region
  the temperatures are the highest just above the limb, and appear
  to decrease with height. These differences may be due to different
  magnetic configurations.

Title: The Hinode X-Ray Telescope (XRT): Camera Design, Performance
    and Operations
Authors: Kano, R.; Sakao, T.; Hara, H.; Tsuneta, S.; Matsuzaki, K.;
   Kumagai, K.; Shimojo, M.; Minesugi, K.; Shibasaki, K.; DeLuca, E. E.;
   Golub, L.; Bookbinder, J.; Caldwell, D.; Cheimets, P.; Cirtain, J.;
   Dennis, E.; Kent, T.; Weber, M.
Bibcode: 2008SoPh..249..263K
Altcode:
  The X-ray Telescope (XRT) aboard the Hinode satellite is a grazing
  incidence X-ray imager equipped with a 2048×2048 CCD. The XRT has
  1 arcsec pixels with a wide field of view of 34×34 arcmin. It is
  sensitive to plasmas with a wide temperature range from &lt; 1 to 30
  MK, allowing us to obtain TRACE-like low-temperature images as well as
  Yohkoh/SXT-like high-temperature images. The spacecraft Mission Data
  Processor (MDP) controls the XRT through sequence tables with versatile
  autonomous functions such as exposure control, region-of-interest
  tracking, flare detection, and flare location identification. Data are
  compressed either with DPCM or JPEG, depending on the purpose. This
  results in higher cadence and/or wider field of view for a given
  telemetry bandwidth. With a focus adjust mechanism, a higher resolution
  of Gaussian focus may be available on-axis. This paper follows the
  first instrument paper for the XRT (Golub et al., Solar Phys.243, 63,
  2007) and discusses the design and measured performance of the X-ray
  CCD camera for the XRT and its control system with the MDP.

Title: The Analysis of Hinode/XRT Observations
Authors: Deluca, E. E.; Weber, M.; Savcheva, A.; Saar, S.; Testa,
   P.; Cirtain, J. W.; Sakao, T.; Noriyuki, N.; Kano, R.; Shimizu, T.
Bibcode: 2008AGUSMSP51B..02D
Altcode:
  This poster will present the current state of Hinode/XRT analysis
  software. We will give an overview of the XRT Analysis Guide. We will
  include a detailed discussion of the following topics: <P />Co-alignment
  with SOT and EIS Spot removal for dynamics studies Filter calibration
  for thermal studies Dark calibrations <P />Sample data sets will be
  discussed and links to the data products will be provided.

Title: Outflows at the Edges of Active Regions: Contribution to
    Solar Wind Formation?
Authors: Harra, L. K.; Sakao, T.; Mandrini, C. H.; Hara, H.; Imada,
   S.; Young, P. R.; van Driel-Gesztelyi, L.; Baker, D.
Bibcode: 2008ApJ...676L.147H
Altcode:
  The formation of the slow solar wind has been debated for many years. In
  this Letter we show evidence of persistent outflow at the edges of
  an active region as measured by the EUV Imaging Spectrometer on board
  Hinode. The Doppler velocity ranged between 20 and 50 km s<SUP>-1</SUP>
  and was consistent with a steady flow seen in the X-Ray Telescope. The
  latter showed steady, pulsing outflowing material and some transverse
  motions of the loops. We analyze the magnetic field around the active
  region and produce a coronal magnetic field model. We determine from
  the latter that the outflow speeds adjusted for line-of-sight effects
  can reach over 100 km s<SUP>-1</SUP>. We can interpret this outflow as
  expansion of loops that lie over the active region, which may either
  reconnect with neighboring large-scale loops or are likely to open to
  the interplanetary space. This material constitutes at least part of
  the slow solar wind.

Title: Erratum: "Outflows at the Edges of Active Regions: Contribution
    to Solar Wind Formation?" (ApJ, 676, L147 [2008])
Authors: Harra, L. K.; Sakao, T.; Mandrini, C. H.; Hara, H.; Imada,
   S.; Young, P. R.; van Driel-Gesztelyi, L.; Baker, D.
Bibcode: 2008ApJ...677L.159H
Altcode:
  No abstract at ADS

Title: Activities in the X-Ray Corona as seen by Hinode X-Ray
    Telescope
Authors: Sakao, Taro
Bibcode: 2008cosp...37.2712S
Altcode: 2008cosp.meet.2712S
  We present observations on the solar corona with the X-Ray Telescope
  (XRT) aboard Hinode. XRT is a grazing-incidence imager with a Walter
  Type-I-like mirror of 34 cm diameter, with a back-illuminated CCD device
  located at its focus position. In addition to its imaging capability for
  the X-ray corona with the highest angular resolution (consistent with 1
  arcsec CCD pixel size) as a solar X-ray telescope, enhanced sensitivity
  of the CCD towards longer X-ray wavelengths (particularly longer than
  50 angstroms) enables XRT to image, and perform temperature diagnostics
  on, coronal plasmas in a wide temperature range (1-10 MK). This adds a
  notable advantage to XRT that it can observe most, if not all, active
  phenomena in the corona throughout their entire thermal evolution. XRT
  has so far revealed various new aspects of coronal activities. These
  include (1) plasma flows in the corona, (2) frequent X-ray jets in the
  polar regions, (3) eruptive events even with small or moderate X-ray
  activities, (4) fine structure and evolution of flaring loops, (5)
  detailed observations on transient brightenings (microflares) in quiet
  as well as active regions. Some highlights of Hinode XRT observations,
  centered on those on plasma flows, will be presented and discussed.

Title: Molecular Contamination Assessments on
    &lt;i&gt;Hinode&lt;/i&gt; X-Ray Telescope
Authors: Urayama, Fumitaka; Bando, Takamasa; Kano, Ryouhei; Hara,
   Hirohisa; Narukage, Noriyuki; Sakao, Taro
Bibcode: 2008JSASS..56..536U
Altcode:
  The &lt;i&gt;Hinode&lt;/i&gt; (Solar-B) was launched by M-V rocket on 22
  September 2006 UT. The telemetry data of the &lt;i&gt;Hinode&lt;/i&gt;
  X-ray Telescope (XRT) showed that the X-ray count rate detected with
  the XRT had decreased rapidly since the operational heaters on the
  XRT telescope tube were turned on. This is attributed to the fact that
  molecular contaminants accumulated onto the CCD with the temperature
  of -60ºC resulting in the degradation of the XRT sensitivity. We baked
  the CCD at the temperature of 35ºC in order to remove the contaminants
  from the CCD surface. However many contaminant spots appeared on the
  surface. We found that major contaminant source existed in the telescope
  tube, and identified the contaminants as diethylhexyl phthalate (DEHP)
  or DEHP-like organics. The mechanisms to yield the contaminant spots
  were discussed.

Title: Relation between coronal temperature and magnetic field
Authors: Narukage, Noriyuki; Kano, Ryouhei; Shiota, Daiko; Sakao, Taro
Bibcode: 2008cosp...37.2184N
Altcode: 2008cosp.meet.2184N
  The solar corona has a wide temperature range from less than 1MK to
  more than 10MK. The X-ray telescope (XRT) on board Hinode satellite
  has 9 X-ray analysis filters to observe the almost of whole coronal
  plasma. Using the data observed with this telescope, we successfully
  derived the coronal temperature around the whole sun. We found that
  coronal structures are nicely classified using the temperature and
  emission measure. The coronal structures were found to depend on the
  length of structure and the heating flux. Furthermore, we calculated
  the coronal potential magnetic field in high spatial resolution using
  the photospheric magnetic field observed with SOHO/MDI. To compare the
  heating flux estimated with coronal temperature and the calculated
  coronal magnetic field might be the great clue to solving the big
  coronal heating question.

Title: Dynamics of active regions observed with Hinode XRT
Authors: Sakao, Taro
Bibcode: 2008cosp...37.2711S
Altcode: 2008cosp.meet.2711S
  We present dynamics of active regions observed with the X-Ray Telescope
  (XRT) aboard Hinode. XRT is a grazing-incidence imager with a Walter
  Type-I-like mirror of 34 cm diameter with a back-illuminated CCD
  device. The XRT can image the X-ray corona of the Sun with angular
  resolution consistent with 1 arcsec CCD pixel size. In addition to
  this unprecedentedly-high angular resolution ever achieved as a solar
  X-ray telescope, enhanced sensitivity of the CCD towards longer X-ray
  wavelengths (particularly beyond 50 Angstroms) enables XRT to image,
  and perform temperature diagnostics on, a wide range of coronal plasmas
  from those as low as 1 MK to high-temperature plasmas even exceeding 10
  MK. This adds a notable advantage to the XRT such that it can observe
  most, if not all, active phenomena taking place in and around active
  regions. Since the beginning of observations with XRT on 23 October
  2006, the XRT has so far made various interesting observations regarding
  active regions. These include (1) continuous outflow of plasmas from
  the edge of a solar active region that is likely to be a source of
  (slow) solar wind, (2) clear signature of eruptions for activities even
  down to GOES B-level, (3) detailed structure and evolution of flaring
  loops, (4) formation of large-scale hot loops around active regions,
  and so on. Dynamic phenomena in and around active regions observed
  with Hinode XRT will be presented and their possible implications to
  the Sun-Earth connection investigation will be discussed.

Title: Cross calibration of soft X-ray telescopes between Hinode/XRT
    and GOES13/SXI
Authors: Narukage, N.; Sakao, T.; Kano, R.; Shimojo, M.; Cirtain,
   J.; Deluca, E.; Nitta, N.; Lemen, J.
Bibcode: 2007AGUFMSH53A1050N
Altcode:
  The X-Ray Telescope (XRT) aboard Hinode satellite is a grazing
  incidence telescope to observe all the coronal features with a wide
  temperature range from less than 1MK to more than 10MK. And the XRT
  has 9 X-ray analysis filters which are optimized to observed the
  almost whole coronal plasma and to derived the coronal temperature
  distribution. Meanwhile, the GOES13 satellite carries a Solar X-ray
  Imager (SXI) to monitor the solar X-rays. The SXI is also a grazing
  incidence telescope and has 7 X-ray filters. The XRT and SXI are
  similar telescopes to observe the dynamic solar corona. On 24 Nov 2006,
  the XRT and SXI-team performed the simultaneous observation for the
  cross calibration between XRT and SXI. In this study, we analyzed
  this data set and checked the actual characteristics of each X-ray
  analysis filter.

Title: Mangetic field properties at the footpoints of solar
    microflares (active-region transient brightenings)
Authors: Shimizu, T.; Kano, R.; Katsukawa, Y.; Kubo, M.; Deluca, E.;
   Ichimoto, K.; Lites, B.; Nagata, S.; Sakao, T.; Shine, R.; Suematsu,
   Y.; Tarbell, T.; Title, A.; Tsuneta, S.
Bibcode: 2007AGUFMSH52C..06S
Altcode:
  Solar active regions produce numerous numbers of small-scale explosive
  energy releases, i.e., microflares, which are captured by imaging
  observations in soft X-rays as transient brightenings of small-scale
  coronal loops. Thanks to advanced performance of X-Ray Telescope (XRT)
  onboard the Hinode satellite, we can investigate finer structure
  of the brightening X-ray sources in more details than we did with
  Yohkoh data. One of important questions on microflares is what causes
  microflares. The simultaneous visible-light observations by the Solar
  Optical Telescope (SOT) allow us to explore magnetic activities
  and magnetic field configuration at the photospheric footpoints
  of brightening loops, giving key observations to investigate the
  question. For our investigations of corona-photosphere magnetic
  coupling, we have established co-alignment between SOT and XRT
  with accuracy better than 1 arcsec (Shimizu et al. 2007, PASJ in
  press). It turns out that Ca II H observations are very useful
  to identify the exact positions of footpoints of X-ray transient
  brightening loops. Small "Kernels" are sometimes observed in Ca II H
  and they may be signature of highly accelerated non-thermal particles
  impinging on chromosphere. As already shown in Shimizu et al.(2002),
  frequent transient brightenings are observed at the locations where
  emerging activities are on going. However, another type of brightening
  triggering mechanism should exist to explain some observed multiple-loop
  brightenings. In the multiple-loop brightenings, multiple loops are
  magnetically in parallel with each other and no apparent magnetic
  activities, such as emerging and canceling, are observed at and near
  the footpoints. This paper will present SOT observations of some
  microflares observed with XRT.

Title: Slipping Magnetic Reconnection in Coronal Loops
Authors: Aulanier, Guillaume; Golub, Leon; DeLuca, Edward E.; Cirtain,
   Jonathan W.; Kano, Ryouhei; Lundquist, Loraine L.; Narukage, Noriyuki;
   Sakao, Taro; Weber, Mark A.
Bibcode: 2007Sci...318.1588A
Altcode:
  Magnetic reconnection of solar coronal loops is the main process that
  causes solar flares and possibly coronal heating. In the standard
  model, magnetic field lines break and reconnect instantaneously at
  places where the field mapping is discontinuous. However, another mode
  may operate where the magnetic field mapping is continuous but shows
  steep gradients: The field lines may slip across each other. Soft
  x-ray observations of fast bidirectional motions of coronal loops,
  observed by the Hinode spacecraft, support the existence of this
  slipping magnetic reconnection regime in the Sun’s corona. This
  basic process should be considered when interpreting reconnection,
  both on the Sun and in laboratory-based plasma experiments.

Title: Evidence for Alfvén Waves in Solar X-ray Jets
Authors: Cirtain, J. W.; Golub, L.; Lundquist, L.; van Ballegooijen,
   A.; Savcheva, A.; Shimojo, M.; DeLuca, E.; Tsuneta, S.; Sakao, T.;
   Reeves, K.; Weber, M.; Kano, R.; Narukage, N.; Shibasaki, K.
Bibcode: 2007Sci...318.1580C
Altcode:
  Coronal magnetic fields are dynamic, and field lines may misalign,
  reassemble, and release energy by means of magnetic reconnection. Giant
  releases may generate solar flares and coronal mass ejections and,
  on a smaller scale, produce x-ray jets. Hinode observations of polar
  coronal holes reveal that x-ray jets have two distinct velocities:
  one near the Alfvén speed (~800 kilometers per second) and another
  near the sound speed (200 kilometers per second). Many more jets were
  seen than have been reported previously; we detected an average of
  10 events per hour up to these speeds, whereas previous observations
  documented only a handful per day with lower average speeds of 200
  kilometers per second. The x-ray jets are about 2 × 10<SUP>3</SUP> to
  2 × 10<SUP>4</SUP> kilometers wide and 1 × 10<SUP>5</SUP> kilometers
  long and last from 100 to 2500 seconds. The large number of events,
  coupled with the high velocities of the apparent outflows, indicates
  that the jets may contribute to the high-speed solar wind.

Title: Continuous Plasma Outflows from the Edge of a Solar Active
    Region as a Possible Source of Solar Wind
Authors: Sakao, Taro; Kano, Ryouhei; Narukage, Noriyuki; Kotoku,
   Jun'ichi; Bando, Takamasa; DeLuca, Edward E.; Lundquist, Loraine L.;
   Tsuneta, Saku; Harra, Louise K.; Katsukawa, Yukio; Kubo, Masahito;
   Hara, Hirohisa; Matsuzaki, Keiichi; Shimojo, Masumi; Bookbinder, Jay
   A.; Golub, Leon; Korreck, Kelly E.; Su, Yingna; Shibasaki, Kiyoto;
   Shimizu, Toshifumi; Nakatani, Ichiro
Bibcode: 2007Sci...318.1585S
Altcode:
  The Sun continuously expels a huge amount of ionized material into
  interplanetary space as the solar wind. Despite its influence on the
  heliospheric environment, the origin of the solar wind has yet to
  be well identified. In this paper, we report Hinode X-ray Telescope
  observations of a solar active region. At the edge of the active region,
  located adjacent to a coronal hole, a pattern of continuous outflow of
  soft-x-ray emitting plasmas was identified emanating along apparently
  open magnetic field lines and into the upper corona. Estimates of
  temperature and density for the outflowing plasmas suggest a mass
  loss rate that amounts to ~1/4 of the total mass loss rate of the
  solar wind. These outflows may be indicative of one of the solar wind
  sources at the Sun.

Title: Fine Thermal Structure of a Coronal Active Region
Authors: Reale, Fabio; Parenti, Susanna; Reeves, Kathy K.; Weber,
   Mark; Bobra, Monica G.; Barbera, Marco; Kano, Ryouhei; Narukage,
   Noriyuki; Shimojo, Masumi; Sakao, Taro; Peres, Giovanni; Golub, Leon
Bibcode: 2007Sci...318.1582R
Altcode:
  The determination of the fine thermal structure of the solar corona is
  fundamental to constraining the coronal heating mechanisms. The Hinode
  X-ray Telescope collected images of the solar corona in different
  passbands, thus providing temperature diagnostics through energy
  ratios. By combining different filters to optimize the signal-to-noise
  ratio, we observed a coronal active region in five filters, revealing
  a highly thermally structured corona: very fine structures in the
  core of the region and on a larger scale further away. We observed
  continuous thermal distribution along the coronal loops, as well as
  entangled structures, and variations of thermal structuring along the
  line of sight.

Title: Magnetic Feature and Morphological Study of X-Ray Bright
    Points with Hinode
Authors: Kotoku, Jun'ichi; Kano, Ryouhei; Tsuneta, Saku; Katsukawa,
   Yukio; Shimizu, Toshifumi; Sakao, Taro; Shibazaki, Kiyoto; Deluca,
   Edward E.; Korreck, Kelly E.; Golub, Leon; Bobra, Monica
Bibcode: 2007PASJ...59S.735K
Altcode:
  We observed X-ray bright points (XBPs) in a quiet region of the Sun
  with the X-Ray Telescope (XRT) aboard the Hinode satellite on 2006
  December 19. XRT's high-resolution X-ray images revealed many XBPs with
  complicated structure and evolving dramatically with time. Almost all
  of the dynamic eruptions in the quiet region were composed of XBPs,
  and they had either loop or multiloop shapes, as is observed in larger
  flares. Brightening XBPs had strong magnetic fields with opposite
  polarities near their footpoints. While we have found a possible
  example of associated magnetic cancellation, other XBPs brighten and
  fade without any associated movement of the photospheric magnetic field.

Title: A Study of Polar Jet Parameters Based on Hinode XRT
    Observations
Authors: Savcheva, Antonia; Cirtain, Jonathan; Deluca, Edward E.;
   Lundquist, Loraine L.; Golub, Leon; Weber, Mark; Shimojo, Masumi;
   Shibasaki, Kiyoto; Sakao, Taro; Narukage, Noriyuki; Tsuneta, Saku;
   Kano, Ryouhei
Bibcode: 2007PASJ...59S.771S
Altcode:
  Hinode/SOHO campaign 7197 is the most extensive study of polar jet
  formation and evolution from within both the north and south polar
  coronal holes so far. For the first time, this study showed that the
  appearance of X-ray jets in the solar coronal holes occurs at very high
  frequency - about 60 jets d<SUP>-1</SUP> on average. Using observations
  collected by the X-Ray Telescope on Hinode, a number of physical
  parameters from a large sample of jets were statistically studied. We
  measured the apparent outward velocity, the height, the width and
  the lifetime of the jets. In our sample, all of these parameters show
  peaked distributions with maxima at 160kms<SUP>-1</SUP> for the outward
  velocity, 5 × 10<SUP>4</SUP> km for the height, 8 × 10<SUP>3</SUP>
  km for the width, and about 10min for the lifetime of the jets. We
  also present the first statistical study of jet transverse motions,
  which obtained transverse velocities of 0-35kms<SUP>-1</SUP>. These
  values were obtained on the basis of a larger (in terms of frequency)
  and better sampled set of events than what was previously statistically
  studied (Shimojo et al. 1996, PASJ, 48, 123). The results were made
  possible by the unique characteristics of XRT. We describe the methods
  used to determine the characteristics and set some future goals. We
  also show that despite some possible selection effects, jets preferably
  occur inside the polar coronal holes.

Title: Hinode Calibration for Precise Image Co-Alignment between
    SOT and XRT (2006 November-2007 April)
Authors: Shimizu, Toshifumi; Katsukawa, Yukio; Matsuzaki, Keiichi;
   Ichimoto, Kiyoshi; Kano, Ryohei; Deluca, Edward E.; Lundquist,
   Loraine L.; Weber, Mark; Tarbell, Theodore D.; Shine, Richard A.;
   Sôma, Mitsuru; Tsuneta, Saku; Sakao, Taro; Minesugi, Kenji
Bibcode: 2007PASJ...59S.845S
Altcode: 2007arXiv0709.4098S
  To understand the physical mechanisms for activity and heating in
  the solar atmosphere, the magnetic coupling from the photosphere
  to the corona is an important piece of information from the Hinode
  observations, and therefore precise positional alignment is required
  among the data acquired by different telescopes. The Hinode spacecraft
  and its onboard telescopes were developed to allow us to investigate
  magnetic coupling with co-alignment accuracy better than 1". Using
  the Mercury transit observed on 2006 November 8 and co-alignment
  measurements regularly performed on a weekly basis, we have determined
  the information necessary for precise image co-alignment, and have
  confirmed that co-alignment better than 1" can be realized between
  Solar Optical Telescope (SOT) and X-Ray Telescope (XRT) with our
  baseline co-alignment method. This paper presents results from the
  calibration for precise co-alignment of CCD images from SOT and XRT.

Title: Hinode Observations of the Onset Stage of a Solar Filament
    Eruption
Authors: Sterling, Alphonse C.; Moore, Ronald L.; Berger, Thomas
   E.; Bobra, Monica; Davis, John M.; Jibben, Patricia; Kano, Ryohei;
   Lundquist, Loraine L.; Myers, D.; Narukage, Noriyuki; Sakao, Taro;
   Shibasaki, Kiyoto; Shine, Richard A.; Tarbell, Theodore D.; Weber, Mark
Bibcode: 2007PASJ...59S.823S
Altcode:
  We used Hinode X-Ray Telescope (XRT) and Solar Optical Telescope (SOT)
  filtergraph (FG) Stokes-V magnetogram observations, to study the
  early onset of a solar eruption that includes an erupting filament
  that we observe in TRACE EUV images. The filament undergoes a slow
  rise for at least 20min prior to its fast eruption and strong soft
  X-ray (SXR) flaring; such slow rises have been previously reported,
  and the new Hinode data elucidate the physical processes occurring
  during this period. XRT images show that during the slow-rise phase,
  an SXR sigmoid forms from apparent reconnection low in the sheared core
  field traced by the filament, and there is a low-level intensity peak
  in both EUV and SXRs during the slow rise. MDI and SOT FG Stokes-V
  magnetograms show that the pre-eruption filament is along a neutral
  line between opposing-polarity enhanced network cells, and the SOT
  magnetograms show that these opposing fields are flowing together
  and canceling for at least six hours prior to eruption. From the MDI
  data we measured the canceling network fields to be ∼ 40G, and we
  estimated that ∼ 10<SUP>19</SUP> Mx of flux canceled during the
  five hours prior to eruption; this is only ∼ 5% of the total flux
  spanned by the eruption and flare, but apparently its tether-cutting
  cancellation was enough to destabilize the sigmoid field holding the
  filament and resulted in that field's eruption.

Title: Fine Structures of Solar X-Ray Jets Observed with the X-Ray
    Telescope aboard Hinode
Authors: Shimojo, Masumi; Narukage, Noriyuki; Kano, Ryohei; Sakao,
   Taro; Tsuneta, Saku; Shibasaki, Kiyoto; Cirtain, Jonathan W.;
   Lundquist, Loraine L.; Reeves, Katherine K.; Savcheva, Antonia
Bibcode: 2007PASJ...59S.745S
Altcode:
  The X-Ray Telescope (XRT) aboard Hinode has revealed the fine structure
  of solar X-ray jets. One of the fine structures observed by XRT is an
  expanding loop. The loop appeared near the footpoint of the jet when
  footpoint brightening was observed. Additionally, we have found that the
  X-ray jets began just after the expanding loop ``breaks''. Other fine
  structures discovered by XRT are thread-like features along the axis
  of the jets. XRT has shown that these thread structures compose the
  cross-section of jets. The fine structures and their motions strongly
  support an X-ray jet model based on magnetic reconnection, and also
  suggest that we must consider the three-dimensional configuration of the
  magnetic field to understand the jet phenomenon. We also investigated
  the reverse jet associated with the X-ray jet in the quiet Sun, and
  propose that the reverse jet is produced by heat conduction, or a MHD
  wave subsequent to the main jet.

Title: Evolution of the Sheared Magnetic Fields of Two X-Class Flares
    Observed by Hinode/XRT
Authors: Su, Yingna; Golub, Leon; van Ballegooijen, Adriaan; Deluca,
   Edward E.; Reeves, Kathy K.; Sakao, Taro; Kano, Ryouhei; Narukage,
   Noriyuki; Shibasaki Kiyoto
Bibcode: 2007PASJ...59S.785S
Altcode:
  We present multi-wavelength observations of the evolution of the sheared
  magnetic fields in NOAA Active Region 10930, where two X-class flares
  occurred on 2006 December 13 and December 14, respectively. Observations
  made with the X-ray Telescope (XRT) and the Solar Optical Telescope
  (SOT) aboard Hinode suggest that the gradual formation of the sheared
  magnetic fields in this active region is caused by the rotation and
  west-to-east motion of an emerging sunspot. In the pre-flare phase
  of the two flares, XRT shows several highly sheared X-ray loops in
  the core field region, corresponding to a filament seen in the TRACE
  EUV observations. XRT observations also show that part of the sheared
  core field erupted, and another part of the sheared core field stayed
  behind during the flares, which may explain why a large part of the
  filament is still seen by TRACE after the flare. About 2-3 hours after
  the peak of each flare, the core field becomes visible in XRT again,
  and shows a highly sheared inner and less-sheared outer structure. We
  also find that the post-flare core field is clearly less sheared than
  the pre-flare core field, which is consistent with the idea that the
  energy released during the flares is stored in the highly sheared
  fields prior to the flare.

Title: An On-Orbit Determination of the On-Axis Point Spread Function
    of the Hinode X-Ray Telescope
Authors: Weber, Mark; Deluca, Edward E.; Golub, Leon; Cirtain,
   Jonathan; Kano, Ryouhei; Sakao, Taro; Shibasaki, Kiyoto; Narukage,
   Noriyuki
Bibcode: 2007PASJ...59S.853W
Altcode:
  The Hinode X-ray Telescope provides unprecedented observations of
  the solar corona in X-rays, due in part to its fine resolution. The
  X-ray point spread function (PSF) was measured before launch at the
  NASA X-ray Calibration Facility to have a FWHM of 0.8''. This paper
  describes the work to verify the PSF measurements using on-orbit
  observations of planetary transits and solar eclipses. Analysis of a
  Mercury transit gives a PSF FWHM = 1.0" ± 0.12".

Title: The Hinode (Solar-B) Mission: An Overview
Authors: Kosugi, T.; Matsuzaki, K.; Sakao, T.; Shimizu, T.; Sone,
   Y.; Tachikawa, S.; Hashimoto, T.; Minesugi, K.; Ohnishi, A.; Yamada,
   T.; Tsuneta, S.; Hara, H.; Ichimoto, K.; Suematsu, Y.; Shimojo, M.;
   Watanabe, T.; Shimada, S.; Davis, J. M.; Hill, L. D.; Owens, J. K.;
   Title, A. M.; Culhane, J. L.; Harra, L. K.; Doschek, G. A.; Golub, L.
Bibcode: 2007SoPh..243....3K
Altcode:
  The Hinode satellite (formerly Solar-B) of the Japan Aerospace
  Exploration Agency's Institute of Space and Astronautical Science
  (ISAS/JAXA) was successfully launched in September 2006. As the
  successor to the Yohkoh mission, it aims to understand how magnetic
  energy gets transferred from the photosphere to the upper atmosphere
  and results in explosive energy releases. Hinode is an observatory
  style mission, with all the instruments being designed and built to
  work together to address the science aims. There are three instruments
  onboard: the Solar Optical Telescope (SOT), the EUV Imaging Spectrometer
  (EIS), and the X-Ray Telescope (XRT). This paper provides an overview
  of the mission, detailing the satellite, the scientific payload, and
  operations. It will conclude with discussions on how the international
  science community can participate in the analysis of the mission data.

Title: The X-Ray Telescope (XRT) for the Hinode Mission
Authors: Golub, L.; DeLuca, E.; Austin, G.; Bookbinder, J.; Caldwell,
   D.; Cheimets, P.; Cirtain, J.; Cosmo, M.; Reid, P.; Sette, A.; Weber,
   M.; Sakao, T.; Kano, R.; Shibasaki, K.; Hara, H.; Tsuneta, S.; Kumagai,
   K.; Tamura, T.; Shimojo, M.; McCracken, J.; Carpenter, J.; Haight,
   H.; Siler, R.; Wright, E.; Tucker, J.; Rutledge, H.; Barbera, M.;
   Peres, G.; Varisco, S.
Bibcode: 2007SoPh..243...63G
Altcode:
  The X-ray Telescope (XRT) of the Hinode mission provides an
  unprecedented combination of spatial and temporal resolution in solar
  coronal studies. The high sensitivity and broad dynamic range of XRT,
  coupled with the spacecraft's onboard memory capacity and the planned
  downlink capability will permit a broad range of coronal studies over
  an extended period of time, for targets ranging from quiet Sun to
  X-flares. This paper discusses in detail the design, calibration, and
  measured performance of the XRT instrument up to the focal plane. The
  CCD camera and data handling are discussed separately in a companion
  paper.

Title: The Dynamics Of Fine Structures In Solar X-ray Jets
Authors: Shimojo, Masumi; Narukage, N.; Kano, R.; Sakao, T.; Tsuneta,
   T.; Cirtain, J. W.; Lundquist, L. L.; Deluca, E. E.; Golub, L.
Bibcode: 2007AAS...210.9422S
Altcode: 2007BAAS...39Q.221S
  The X-ray telescope(XRT) aboard HINODE satellite has the great
  spatial/time resolution in X-ray range. And, the observations using
  XRT have revealed the fine structures of solar corona. From the
  observations, we found the fine thread structures in the X-ray jets
  and the structures move dynamically like wave. We also found that some
  X-ray jets start just after small loop expansion in the footpoint
  brightening. The observation results suggest that the reconnection
  process X-ray jets is very similar to that in large flares.

Title: Hinode Data Calibration For Precise Image Co-alignment:
    XRT vs. SOT
Authors: Shimizu, Toshifumi; DeLuca, E. E.; Lundquist, L.; Sakao,
   T.; Kubo, M.; Narukage, N.; Kano, R.; Katsukawa, Y.; Ichimoto, K.;
   Suematsu, Y.; Tsuneta, S.; Tarbell, T.; Shine, D.; Hinode Team
Bibcode: 2007AAS...210.9417S
Altcode: 2007BAAS...39Q.220S
  From late October in 2006, Hinode solar optical telescope (SOT) has
  started to produce series of 0.2-0.3 arcsec visible-light images,
  revealing dynamical behaviors of solar magnetic fields on the
  solar surface. Simultaneously, Hinode X-ray telescope (XRT) has been
  providing 1 arcsec resolution X-ray images of the solar corona, giving
  the location of heating and dynamics occuring in the corona. Precise
  image co-alignment of SOT data on XRT data with sub-arcsec accuracy is
  required to provide new information regarding connecting the corona to
  the photosphere. This presentation will give an introduction of Hinode
  between-telescopes' image co-alignment to SPD participants. For active
  region observations with sunspots, sunspots can be used as fiducial to
  co-align the data from the two telescopes each other. Satellite jitter
  in order of 1 arcsec or less is included in the series of XRT data,
  whereas image stabilization system (correlation tracker) removes the
  satellite jitter from the series of SOT images. Telescope pointings show
  orbital variation in order of a few arcsec, which can be well predicted
  from Hinode orbit information. Modeling co-alignment is under study
  and it is the only precise method for quiet Sun and limb observations.

Title: Coronal Temperature Diagnostics With Hinode X-ray Telescope
Authors: Narukage, Noriyuki; Sakao, T.; Kano, R.; Shimojo, M.; Tsuneta,
   S.; Kosugi, T.; Deluca, E. E.; Golub, L.; Weber, M.; Cirtain, J.;
   Japan-US X-Ray Telescope Team
Bibcode: 2007AAS...210.6304N
Altcode: 2007BAAS...39..172N
  An X-ray telescope (XRT) on board HINODE satellite observes the Sun
  in X-rays with high special resolution (1arcsec 730km on solar the
  disk). This telescope has 9 X-ray filters with different temperature
  responses. Using these filters, the XRT can detect the coronal
  plasma with a wide temperature range from less than 1MK to more
  than 10MK. Moreover, based on observations with more than 2 filters,
  we can estimate the coronal temperature. In this paper, we use the
  filter ratio method for coronal temperature diagnostics. Using this
  method, we can easily estimate the averaged temperature of the coronal
  plasma along the line-of-sight. This method has been used frequently
  in the past, but the high quality XRT data give us temperature maps
  with unprecedented accuracy and resolution. The XRT usually takes
  the full Sun images with 2 kinds of filters 4 times a day. Using this
  data and filter ratio method, we can obtain full Sun temperature maps
  with high special resolution. In our analysis, we can derive reliable
  temperatures not only in active regions but also in quiet regions and
  coronal holes. This map can be created with the data set of one synoptic
  observation. This means that we can obtain 4 maps a day. The result is
  a full Sun temperature movie that gives us an unprecedented view of the
  time evolution of solar temperature. In this meeting, we will show the
  full Sun temperature movie and our coronal temperature analysis results.

Title: Continuous Upflow of Plasmas at the Edge of an Active Region
    as Revealed by the X-ray Telescope (XRT) aboard Hinode
Authors: Sakao, Taro; Kano, R.; Narukage, N.; Kotoku, J.; Bando, T.;
   DeLuca, E. E.; Lundquist, L. L.; Golub, L.; Kubo, M.; Katsukawa, Y.;
   Tsuneta, S.; Hara, H.; Matsuzaki, K.; Shimojo, M.; Shibasaki, K.;
   Shimizu, T.; Nakatani, I.
Bibcode: 2007AAS...210.7205S
Altcode: 2007BAAS...39Q.179S
  We present X-ray imaging observations with Hinode X-Ray Telescope (XRT)
  of an active region NOAA AR 10942 made in the period of 20-22 February
  2007. A prominent feature that drew our particular attention is that
  there revealed continuous upflow of soft-X-ray-emitting plasmas along
  apparently-open field lines towards the outer corona emanating from the
  edge of the active region. <P />The field lines are originated from
  an ensamble of small spots of following polarity, and are located at
  a border between the active region and an adjacent equatorial coronal
  hole(s) located to the east. The upflow was observed to be continuous
  throughout the three days of observation intervals with projected
  velocity of 140 km/s, accompanied with undulating motion of the field
  lines. <P />We assert that these upflowing plasmas would be a possible
  source of slow solar wind material, which supports a foresighted
  notion which grew out of interplanetary scintillation observations
  that slow solar wind most likely has its origin in the vicinity of
  active regions with large flux expansion (Kojima et al. 1999). <P />A
  preliminaty analysis indicates that the temperature of the upflowing
  material near the base of the field lines is 1.3 MK with number density
  of 2 × 10<SUP>9 </SUP>/cm<SUP>3</SUP>. Assuming that all the material
  is to escape to the interplanetary space, this leads to a mass loss
  rate of 2 × 10<SUP>11</SUP> g/s which amounts to a good fraction of
  the total mass loss rate for solar wind. It is noteworthy that, even
  apart from this unique upflow, we see continuous (up)flows of plasmas
  anywhere around (surrounding) the active region. <P />Details of the
  upflow will be presented and their possible implication to slow solar
  wind discussed.

Title: Structure and Coronal Activity around Filament Channels
    Observed with Hinode XRT And TRACE
Authors: Lundquist, Loraine L.; van Ballegooijen, A. A.; Reeves,
   K. K.; Sakao, T.; DeLuca, E. E.; Narukage, N.; Kano, R.
Bibcode: 2007AAS...210.9427L
Altcode: 2007BAAS...39..221L
  The combination of multi-wavelength, high resolution, high cadence
  data from the Hinode X-Ray Telescope (XRT) and the Transition Region
  And Coronal Explorer (TRACE) give an unprecedented view of solar
  active region dynamics and coronal topology. We focus on examples of
  filament structures observed by TRACE and XRT in December 2006 and
  February 2007. Co-alignment of observations in these two instruments
  yields a striking picture of the coronal structures, with loops lying
  both along and above the filament. Overlying loops exhibit remarkable
  dynamics while the filament lies dormant, and numerous x-point and
  triple-leg structures undergo repeated brightenings. We also employ
  magnetic field data from SOT and from SOLIS to compare a non-linear
  force-free model of the coronal magnetic field with the observed loops.

Title: Temperature Structures Above Coronal Hole and Quiet Sun
Authors: Kano, Ryouhei; Sakao, T.; Narukage, N.; Kotoku, J.; Bando,
   T.; DeLuca, E. E.; Lundquist, L.; Golub, L.; Tsuneta, S.; Hara, H.;
   Shibasaki, K.; Shimojo, M.
Bibcode: 2007AAS...210.9436K
Altcode: 2007BAAS...39..223K
  The X-ray Telescope (XRT) on board Hinode satelite has the capability
  to derive the temperature structure in the solar corona. We present
  the hieght dependence of the temperature above the limb. Because X-ray
  intensity above the limb is so faint, it is important to estimate the
  scattered light from disk corona. The eclipses happened on February 17
  and March 19 in 2007 at Hinode orbit. On February 17, we took X-ray
  images above the south polar coronal hole, while Moon passed it. On
  March 19, we took the data for quiet Sun in the same way. <P />We
  can estimated the scattered light from the eclipse data, and derived
  the scatter-free X-ray images above the solar limb. In this meeting,
  we will present the temperatures above coronal hole and quiet Sun,
  based on the eclipse data.

Title: Particle Acceleration in the X3 Event on Dec. 13, 2007
Authors: Shibasaki, Kiyoto; Koshiishi, H.; Shimojo, M.; Minoshima,
   T.; Imada, S.; Sakao, T.; Hinode Team
Bibcode: 2007AAS...210.9435S
Altcode: 2007BAAS...39..223S
  Even during the solar minimum period, the active region NOAA 10930 had
  a complex magnetic configuration especially around the main sunspot
  and produced a couple of X-class events. The one on Dec. 13, 2007 was
  well observed by Nobeyama Radioheliograph (NoRH) and Polarimeters
  (NoRP). Microwave emission associated with this event has several
  interesting characteristics: <P />1. Long lasting non-thermal phase <P
  />2. Very large decimetric flux (several thousand times of the quiet
  sun flux) and quite different time development of decimetric emission
  compared to shorter wavelengths <P />3. Very high turn-over frequency
  (around 35 GHz) <P />This event was also well observed by HINODE
  satellite and partially by RHESSI satellite. Optical telescope (SOT) and
  Soft X-ray telescope (XRT) onboard HINODE showed that the flare started
  around the polarity reversal line which divides the main sunspot and
  the closely associated small sunspot with opposite polarity. This line
  is the interface of the penumbrae of both sunspots. The flare ribbons
  started in the penumbrae and entered into umbrae of both sunspots. <P
  />Microwave images of the event at 17 and 34 GHz are synthesized
  and compared with optical and soft X-ray images taken by SOT and XRT
  respectively. Based on these overlays, frequency spectral information
  (NoRP) and RHESSI images in the later phase of the event, we try to
  locate particle acceleration site and discuss possible mechanisms of
  acceleration. <P />Hinode is an international project supported by JAXA,
  NASA, PPARC and ESA. We are grateful to the Hinode team for all their
  efforts in the design, development and operation of the mission. NoRH
  and NoRP are operated by Nobeyama Solar Radio Observatory, NAOJ. RHESSI
  is a NASA project.

Title: Magnetic activity and the solar corona: first results from
    the Hinode satellite .
Authors: Reale, Fabio; Parenti, Susanna; Reeves, Kathy K.; Weber,
   Mark; Bobra, Monica G.; Barbera, Marco; Kano, Ryohei; Narukage,
   Noriyuki; Shimojo, Masumi; Sakao, Taro; Peres, Giovanni; Golub, Leon
Bibcode: 2007MmSAI..78..591R
Altcode:
  The structure, dynamics and evolution of the solar corona are governed
  by the magnetic field. In spite of significant progresses in our insight
  of the physics of the solar corona, several problems are still under
  debate, e.g. the role of impulsive events and waves in coronal heating,
  and the origin of eruptions, flares and CMEs. The Hinode mission has
  started on 22 september 2006 and aims at giving new answers to these
  questions. The satellite contains three main instruments, two high
  resolution telescopes, one in the optical and one in the X-ray band,
  and an EUV imaging spectrometer. On the Italian side, INAF/Osservatorio
  Astronomico di Palermo has contributed with the ground-calibration
  of the filters of the X-ray telescope. We present some preliminary
  mission results, with particular attention to the X-ray telescope data.

Title: Energetics and Dynamics of an Impulsive Flare on March 10, 2001
Authors: Chandra, Ramesh; Jain, Rajmal; Uddin, Wahab; Yoshimura,
   Keiji; Kosugi, Takeo; Sakao, Taro; Joshi, Anita; Deshpande, M. R.
Bibcode: 2006SoPh..239..239C
Altcode: 2006astro.ph..2611C; 2006SoPh..tmp...96C
  We present Hα observations from ARIES (Nainital) of a compact and
  impulsive solar flare that occurred on March 10, 2001 and which
  was associated with a CME. We have also analyzed HXT, SXT/Yohkoh
  observations as well as radio observations from the Nobeyama Radio
  Observatory to derive the energetics and dynamics of this impulsive
  flare. We coalign the Hα, SXR, HXR, MW, and magnetogram images within
  the instrumental spatial-resolution limit. We detect a single HXR
  source in this flare, which is found spatially associated with one of
  the Hα bright kernels. The unusual feature of HXR and Hα sources,
  observed for the first time, is the rotation during the impulsive phase
  in a clockwise direction. We propose that the rotation may be due to
  asymmetric progress of the magnetic reconnection site or may be due
  to the change of the peak point of the electric field. In MW emission
  we found two sources. The main source is at the main flare site and
  another is in the southwest direction. It appears that the remote
  source is formed by the impact of accelerated energetic electrons from
  the main flare site. From the spatial correlation of multiwavelength
  images of the different sources, we conclude that this flare has a
  three-legged structure.

Title: The Motions of the Hard X-Ray Sources in Solar Flares: Images
    and Statistics
Authors: Bogachev, Sergey A.; Somov, Boris V.; Kosugi, Takeo;
   Sakao, Taro
Bibcode: 2005ApJ...630..561B
Altcode:
  On the basis of the Yohkoh Hard X-Ray Telescope (HXT) data, we
  present a statistical study of different types of the hard X-ray
  (HXR) source motions during solar flares. A total of 72 flares that
  occurred from 1991 September to 2001 December have been analyzed. In
  these flares, we have found 198 intense HXR sources that are presumably
  the chromospheric footpoints of flare loops. The average velocity V and
  its uncertainty σ were determined for these sources. For 80% of them,
  the ratio of V to 3 σ is larger than 1, strongly suggesting that (1)
  the moving sources are usually observed rather than stationary ones and
  (2) the regular displacements of HXR sources dominate their chaotic
  motions. After co-alignment of the HXT images with the photospheric
  magnetograms, we have conducted an additional analysis of 31 flares
  out of 72 and distinguished between three main types of the footpoint
  motions. Type I consists of the motions preferentially away from and
  nearly perpendicular to the neutral line (NL). About 13% of flares
  (4 out of 31) show this pattern. In type II, the sources move mainly
  along the NL in antiparallel directions. Such motions have been found
  in 26% of flares (8 out of 31). Type III involves a similar pattern
  as type II, but all the HXR sources move in the same direction along
  the NL. Flares of this type constitute 35% (11 out of 31). In 26%
  of flares (8 out of 31) we observed more complicated motions that can
  be described as a combination of the basic types or some modification
  of them. For the most interesting flares, the results of analysis are
  illustrated and interpretation is suggested.

Title: Contamination evaluation and thermal vacuum bakeout for
    SOLAR-B visible-light and X-ray telescope
Authors: Tamura, Tomonori; Hara, Hirohisa; Tsuneta, Saku; Ichimoto,
   Kiyoshi; Kumagai, Kazuyoshi; Nakagiri, Masao; Shimizu, Toshifumi;
   Sakao, Taro; Kano, Ryouhei
Bibcode: 2005RNAOJ...8...21T
Altcode:
  In the development of space telescopes, we are concerned about molecular
  outgassing materials from telescope components. In particular, for
  solar telescopes in space, the deposition of the outgassing materials
  may lead to the increase of solar absorptance at a mirror surface
  and it causes the thermal distortion due to the resultant temperature
  increase. The mirror reflectivity at vacuum ultraviolet wavelengths
  is very sensitive to molecular contamination. We have extensively
  evaluated reflectance at 121.6nm (Lyman-alpha) of the contamination
  witness mirrors exposed to the telescope testing environments in the
  SOLAR-B visible-light telescope program. Thermal vacuum bakeout of
  flight components is very effective process to reduce the outgassing
  rate. We have severe contamination control program during the assembly
  and testing of the SOLAR-B telescope up to launch of the satellite.

Title: Development of Heater control equipment for the Solar-B XRT
    thermal vacuum test
Authors: Kumagai, Kazuyoshi; Kano, Ryohei; Hara, Hirohisa; Tamura,
   Tomonori; Sawa, Masaki; Tsuneta, Saku; Sakao, Taro; Matsuzaki, Keiichi
Bibcode: 2005RNAOJ...8...29K
Altcode:
  The thermal vacuum test of the X-ray Telescope (XRT) aboard the
  Solar-B satellite was carried out at NASA/Goddard Space Flight Center
  (GSFC) since January 2004. For this thermal test, we developed the
  Heater Sensor GSE (HS-GSE). It is an equipment to record flight
  temperature sensors in the X-ray camera and to control flight camera
  heaters. During the GSFC thermal test, the HS-GSE successfully recorded
  the camera temperatures every 10 seconds, and controlled the heaters
  automatically. We report the system of the HS-GSE successfully recorded
  the camera temperatures every 10 seconds, and controlled the heaters
  automatically. We report the system of the HS-GSE with the results in
  the thermal test.

Title: On upward motions of coronal hard X-ray sources in solar flares
Authors: Somov, B. V.; Kosugi, T.; Bogachev, S. A.; Masuda, S.;
   Sakao, T.
Bibcode: 2005AdSpR..35.1690S
Altcode:
  Coronal hard X-ray (HXR) sources were discovered by the Yohkoh
  HXT telescope in about two dozen limb flares: Impulsive and gradual
  ones. On the basis of HXT data, we investigated the spatial evolution of
  coronal sources. Slow ascending motions of sources are seen in several
  flares. In five events, it was possible to estimate the velocity
  of the upward motion with values between 10 and 30 km/s. We present
  these observational results and conclude that coronal source motions
  should be studied statistically using the RHESSI high-resolution HXR
  imaging data. We discuss the possibility that coronal HXR emission
  is generated as bremsstrahlung of the fast electrons accelerated
  in collapsing magnetic traps due to joint action of the Fermi-type
  first-order mechanism and betatron acceleration.

Title: Motion of the HXR sources in solar flares: Yohkoh images
    and statistics
Authors: Somov, B. V.; Kosugi, T.; Bogachev, S. A.; Sakao, T.;
   Masuda, S.
Bibcode: 2005AdSpR..35.1700S
Altcode:
  Using the Yohkoh Hard X-Ray Telescope (HXT) data, we have examined
  motions of the hard X-ray (HXR) sources during 72 solar flares occurred
  from 1991 September to 2001 December. In these flares, we have found
  198 intense sources that are presumably the chromospheric footpoints
  (FPs) of flare loops. The average velocity V and the velocity dispersion
  σ were determined by a linear regression for these sources. For 80%
  of them, the ratio of V to 3 σ is larger than 1, strongly suggesting
  that the regular motions of the HXR sources dominate their chaotic
  motions. For 43 of 72 flares, coalignment of the HXT images with
  the photospheric magnetograms allows us to consider the HXR sources
  located on the both sides of the photospheric neutral line (NL) as
  the FP sources, and to distinguish between three main types of the FP
  motions. The type I is the motions of the HXR sources preferentially
  away from and nearly perpendicular to the NL. Less than 5% of the flares
  show this pattern of motion. In the type II, the sources move mainly
  along the NL in anti-parallel directions. Such motions have been found
  in 26% of flares. The type III involves a similar pattern of motions as
  the type II but all the HXR sources move in the same direction along
  the NL. Flares of this type constitute 30% of the flares. About 19%
  of flares can be described as a combination of these basic types. The
  remaining 20% of flares seem to be more complicated or less regular
  in the motion scale under consideration. An interpretation of results
  is suggested.

Title: The first build-up of the Solar-B flight models
Authors: Hara, Hirohisa; Ichimoto, Kiyoshi; Otsubo, Masashi; Katsukawa,
   Yukio; Kato, Yoshihiro; Kano, Ryohei; Kumagai, Kazuyoshi; Shibasaki,
   Kiyoto; Shimizu, Toshifumi; Shimojo, Masumi; Suematsu, Yoshinori;
   Tamura, Tomonori; Tsuneta, Saku; Noguchi, Motokazu; Nakagiri, Masao;
   Miyashita, Masakuni; Watanabe, Tesuya; Kosuchi, Takeo; Sakao, Taro;
   Matsuzaki, Keiichi; Kitakoshi, Yasunori; Kubo, Masahito; Sakamoto,
   Yasushi
Bibcode: 2005ARAOJ...7...46H
Altcode:
  No abstract at ADS

Title: Science of the X-ray Sun: The X-ray telescope on Solar-B
Authors: DeLuca, E. E.; Weber, M. A.; Sette, A. L.; Golub, L.;
   Shibasaki, K.; Sakao, T.; Kano, R.
Bibcode: 2005AdSpR..36.1489D
Altcode:
  The X-Ray Telescope (XRT) on Solar-B is designed to provide high
  resolution, high cadence observations of the X-ray corona through
  a wide range of filters. The XRT science team has identified four
  general problems in coronal physics as the primary science goals for our
  instrument. Each of these goals will require collaborative observations
  from the other Solar-B instruments: EUV Imaging Spectrograph (EIS)
  and Solar Optical Telescope Focal Plane Package (SOT). We will discuss
  the science goals and observations needed to address those goals.

Title: SolarB X-Ray Telescope (XRT)
Authors: Kano, R.; Hara, H.; Shimojo, M.; Tsuneta, S.; Sakao, T.;
   Matsuzaki, K.; Kosugi, T.; Golub, L.; Deluca, E. E.; Bookbinder,
   J. A.; Cheimets, P.; Owens, J. K.; Hill, L. D.
Bibcode: 2004ASPC..325...15K
Altcode:
  The Soft X-ray Telescope (XRT) aboard SolarB is a grazing incidence
  X-ray telescope equipped with 2k × 2k CCD. XRT has 1 arcsec resolution
  with wide field-of-view of 34 × 34 arcmin. It is sensitive to
  &lt;1 MK to 30 MK, allowing us to obtain TRACE-like low temperature
  images as well. Co-alignment with SOT and EIS is realized through
  the XRT visible light telescope and with temperature overlap with
  EIS. Spacecraft mission data processor (MDP) controls XRT through
  the sequence tables with versatile autonomous functions such as
  exposure control, region-of-interest tracking, flare detection and
  flare location identification. Data are compressed either with DPCM or
  JPEG, depending on the purpose. This results in higher cadence and/or
  wider field-of-view for given telemetry bandwidth. With focus adjust
  mechanism, higher resolution of Gaussian focus may be available on-axis.

Title: Multi-Wavelength Observations of an Unusual Impulsive Flare
    Associated with Cme
Authors: Uddin, Wahab; Jain, Rajmal; Yoshimura, Keiji; Chandra,
   Ramesh; Sakao, T.; Kosugi, T.; Joshi, Anita; Despande, M. R.
Bibcode: 2004SoPh..225..325U
Altcode: 2004astro.ph.10177U
  We present the results of a detailed analysis of multi-wavelength
  observations of a very impulsive solar flare 1B/M6.7, which occurred on
  10 March, 2001 in NOAA AR 9368 (N27 W42). The observations show that the
  flare is very impulsive with a very hard spectrum in HXR that reveal
  that non-thermal emission was most dominant. On the other hand, this
  flare also produced a type II radio burst and coronal mass ejections
  (CME), which are not general characteristics for impulsive flares. In
  Hα we observed bright mass ejecta (BME) followed by dark mass ejecta
  (DME). Based on the consistency of the onset times and directions
  of BME and CME, we conclude that these two phenomena are closely
  associated. It is inferred that the energy build-up took place due to
  photospheric reconnection between emerging positive parasitic polarity
  and predominant negative polarity, which resulted as a consequence
  of flux cancellation. The shear increased to &gt;80° due to further
  emergence of positive parasitic polarity causing strongly enhanced
  cancellation of flux. It appears that such enhanced magnetic flux
  cancellation in a strongly sheared region triggered the impulsive flare.

Title: Focal plane CCD camera for the X-Ray Telescope (XRT) aboard
    SOLAR-B
Authors: Sakao, Taro; Kano, Ryouhei; Hara, Hirohisa; Matsuzaki,
   Keiichi; Shimojo, Masumi; Tsuneta, Saku; Kosugi, Takeo; Shibasaki,
   Kiyoto; Kumagai, Kazuyoshi; Sawa, Masaki; Tamura, Tomonori; Iwamura,
   Satoru; Nakano, Mitsuhiko; Du, Zhangong; Hiyoshi, Kenji; Horii,
   Michihiro; Golub, Leon; Bookbinder, Jay A.; Cheimets, Peter C.; Hill,
   Lawrence D.; Owens, Jerry K.
Bibcode: 2004SPIE.5487.1189S
Altcode:
  We present scientific as well as engineering overview of the X-Ray
  Telescope (XRT) aboard the Japanese Solar-B mission to be launched in
  2006, with emphasis on the focal plane CCD camera that employs a 2k
  x 2k back-thinned CCD. Characterization activities for the flight CCD
  camera made at the National Astronomical Observatory of Japan (NAOJ)
  are discussed in detail with some of the results presented.

Title: Design and Performance of Tip-Tilt Mirror System for Solar
    Telescope
Authors: Kodeki, Kazuhide; Fukushima, Kazuhiko; Hara, Hirohisa; Inoue,
   Masao; Kano, Ryouhei; Kashiwase, Toshio; Nagata, Shin'ichi; Sakao,
   Taro; Shimizu, Toshifumi; Tsuneta, Saku; Yoshida, Tsuyoshi
Bibcode: 2004JSpRo..41..868K
Altcode:
  No abstract at ADS

Title: Impulsive Solar Flares associated with Coronal Mass Ejections
Authors: Jain, R.; Uddin, W.; Kosugi, T.; Kumar, S.; Chandra, R.;
   Sakao, T.; Masuda, S.
Bibcode: 2004cosp...35..939J
Altcode: 2004cosp.meet..939J
  We present the multi-wavelength observations of a few impulsive
  solar flares, which are associated with Coronal Mass Ejections (CMEs)
  during Solar Cycle 23. The optical and radio waveband observations
  of the solar flares considered for this investigation were made in
  India and Japan, while SOHO, CGRO, YOHKOH and SOXS missions made the
  other wavelength observations. We present the optical, radio and X-ray
  emission characteristics of impulsive flares associated with CMEs in
  view of their energy release and particle acceleration. We conjecture
  a qualitative model to interpret our multi-spectral observations
  of these impulsive solar flares. It is proposed that a CME of some
  magnitude precede the impulsive solar flares to cause strong particle
  acceleration as observed in them. In support of our this concept
  we present the magnetograms of the active regions that reveal the
  cancellation of magnetic flux in all such impulsive events, which in
  turn results in generating a CME as seen in different wavelengths.

Title: Development of the Solar-B X-ray telescope focal plane camera
Authors: Kano, Ryouhei; Hara, Hirohisa; Kumagai, Kazuyoshi; Sawa,
   Masaki; Tsuneta, Saku; Sakao, Taro; Matsuzaki, Keiichi
Bibcode: 2004naoj.book....5K
Altcode:
  No abstract at ADS

Title: Motion of the HXR Sources in Solar Flares: Yohkoh Images
    and Statistics
Authors: Somov, B.; Kosugi, T.; Bogachev, S. A.; Sakao, T.; Masuda, S.
Bibcode: 2004cosp...35...13S
Altcode: 2004cosp.meet...13S
  Using Yohkoh Hard X-ray Telescope (HXT) data of seventy solar flares,
  we have synthesized about 20000 images and compared them with the
  SOHO MDI and Kit Peak magnetograms. This allowed us to study apparent
  motions of the HXR sources in flares. More than 90 % of sources show
  well-defined motions in some directions during the impulsive phase
  of flares. The apparent displacement, i.e. the distance between the
  source positions at the start and at the end of a flare, can reach more
  than 10''. We present here some examples and statistical results. A
  relationship between the direction of a motion and the magnetic field
  configuration in an active region is considered in terms of the rainbow
  reconnection model. The possibility of similar research based on the
  RHESSI data is discussed.

Title: On the Upward Motion of the Coronal HXR Sources in Solar
Flares: Observational and Interpretation Problems
Authors: Somov, B.; Kosugi, T.; Masuda, S.; Sakao, T.; Bogachev, S. A.
Bibcode: 2004cosp...35...14S
Altcode: 2004cosp.meet...14S
  The coronal hard X-ray (HXR) sources were discovered by the Yohkoh
  HXT telescope in about a dozen of impulsive flares as well as in
  some gradual flares called Long Decay Events (LDEs). On the basis of
  the HXT data we have studied the spatial evolution of the coronal
  HXR source in these flares. The ascent motions are seen in several
  flares. However, in a few of them, we could estimate with a good
  accuracy the upward component of velocity of about 10-30 km/sec. We
  present these observational results, consider implications of them for
  the magnetic reconnection flare models and discuss some difficulties of
  interpretation. We conclude that the problem should be studied better
  by using the RHESSI high-resolution HXR imaging data.

Title: Spatial and Temporal Properties of Hot and Cool Coronal Loops
Authors: Nagata, Shin'ichi; Hara, Hirohisa; Kano, Ryouhei; Kobayashi,
   Ken; Sakao, Taro; Shimizu, Toshifumi; Tsuneta, Saku; Yoshida, Tsuyoshi;
   Gurman, Joseph B.
Bibcode: 2003ApJ...590.1095N
Altcode:
  A suite of images from the XUV Doppler Telescope (XDT), the Yohkoh Soft
  X-ray Telescope (SXT), and the Extreme-Ultraviolet Imaging Telescope
  (EIT) on the Solar and Heliospheric Observatory (SOHO) allow us to
  see the whole (T&gt;1 MK) temperature evolution of coronal loops. The
  detailed morphological comparison of an active region shows that hot
  loops seen in SXT (T&gt;3 MK) and cool loops seen in the the EIT 195
  Å band (T~1.5 MK) are located in almost alternating manner. The
  anticoincidence of the hot and the cool loops is conserved for a
  duration much longer than the estimated cooling timescale. However, both
  hot and cool loops have counterparts in the intermediate-temperature
  images. The cross-correlation coefficients are higher for neighboring
  temperature pairs and lower for pairs with larger temperature
  differences. These results suggest that loops are not isothermal but
  rather have a differential emission measure distribution of modest but
  finite width that peaks at different temperatures for different loops.

Title: Basic Principles and Examples of Solar-type Flare Modelling
Authors: Somov, B. V.; Kosugi, T.; Sakao, T.
Bibcode: 2003ASPC..289..393S
Altcode: 2003aprm.conf..393S
  We review the fundamental ideas which are under current use
  to model flares and other non-stationary phenomena in the solar
  atmosphere. Recent multi-wavelength observations of solar flares allow
  us to improve a theory of solar-type flares, which can be applied
  to many astrophysical phenomena accompanied by fast plasma ejection,
  powerful fluxes of radiation, and the acceleration of electrons and
  ions to high energies.

Title: Development of the Solar-B spacecraft
Authors: Tsuneta, Saku; Ichimoto, Kiyoshi; Suematsu, Yoshinori;
   Shimizu, Toshifumi; Hara, Hirohisa; Kano, Ryohei; Nagata, Shin'ichi;
   Tamura, Tomonori; Nakagiri, Masao; Noguchi, Motokazu; Kato, Yoshihiro;
   Watanabe, Tetsuya; Hanaoka, Yoichiro; Sawa, Masaki; Otsubo, Masashi;
   Kosugi, Takeo; Yamada, Takahiro; Sakao, Taro; Matsuzaki, Keiichi;
   Minesugi, Kenji; Onishi, Akira; Katsukawa, Yukio; Kobayashi, Ken;
   Kubo, Masahito
Bibcode: 2003naoj.book....3T
Altcode:
  No abstract at ADS

Title: Modeling large solar flares
Authors: Somov, B. V.; Kosugi, T.; Hudson, H. S.; Sakao, T.; Masuda, S.
Bibcode: 2003AdSpR..32.2439S
Altcode:
  The basic ideas to model the large solar flares are reviewed and
  illustrated. Some fundamental properties of potential and non-potential
  fields in the solar atmosphere are recalled. In particular, we consider
  a classification of the non-potential fields or, more exactly, related
  electric currents, including reconnecting current layers. The so-called
  'rainbow reconnection' model is presented with its properties and
  predictions. This model allows us to understand main features of large
  flares in terms of reconnection. We assume that in the two-ribbon
  flares, like the Bastille-day flare, the magnetic separatrices are
  involved in a large-scale shear photospheric flow in the presence of
  reconnecting current layers generated by a converging flow.

Title: On the Impulsive Solar Flare of 10 March 2001
Authors: Jain, Rajmal; Uddin, Wahab; Kosugi, Takeo; Chandra, Ramesh;
   Keiji, Yoshimura; Sakao, Taro; Joshi, Anita; Deshpande, Mohan R.
Bibcode: 2003IAUJD...7E...5J
Altcode:
  We present the observations of an impulsive solar flare of 10 March
  2001. The flare was observed with Solar Tower Telescope at State
  Observatory Nainital India and space-borne missions viz. YOHKOH
  and SOHO and many other ground-based observatories. The flare was
  associated with intense and impulsive hard X-ray emission. Our analysis
  show that the energy build up took place as a result of photospheric
  reconnection which in turn however was going on with increasing shear
  in the active region from 60 to almost 90 deg. on 10 March 2001. In
  context to multiwavelength radio polarization data from Nobeyama
  and magnetograms from MDI/SOHO it further appears that emerging flux
  region was the source for triggering the impulsive flare as well as
  coronal mass ejection. The alignment of H-alpha images with soft and
  hard X-ray images as well as MW radio images enable us to identify
  the flare sources in different wavelengths. We propose a model to
  interpret our observations and results of this flare event.

Title: Magnetic Reconnection Scenario of the Bastille Day 2000 Flare
Authors: Somov, Boris V.; Kosugi, Takeo; Hudson, Hugh S.; Sakao,
   Taro; Masuda, Satoshi
Bibcode: 2002ApJ...579..863S
Altcode:
  On the basis of Yohkoh Hard X-Ray Telescope data and the magnetograms
  taken by the SOHO Michelson Doppler Imager and the Solar Magnetic
  Field Telescope at Huairou Solar Observing Station, we suggest an
  interpretation of the well-observed ``Bastille Day 2000'' flare. The
  large-scale structure and dynamics of the flare, as seen in hard X-rays,
  can be explained in terms of the three-dimensional reconnection at
  a separator in the corona. More specifically, we suggest that before
  occurrence of two-ribbon flares with significant decrease of a distance
  between the hard X-ray (HXR) footpoints, like the Bastille Day flare,
  the bases of magnetic field separatrices are moved by the large-scale
  photospheric flows of two types. First, the shear flows, which are
  parallel to the photospheric neutral line, increase the length of field
  lines in the corona and produce an excess of magnetic energy. Second,
  the converging flows, i.e., the flows directed to the neutral line,
  create the preflare current layers in the corona and provide an excess
  of energy sufficient to produce a large flare. During the flare, both
  excesses of magnetic energy are released completely or partially. In
  the Bastille Day flare, the model describes two kinds of apparent
  motions of the HXR kernels. One is an increase of a distance between
  the flare ribbons in which the HXR kernels appear. The effect results
  from fast reconnection in a coronal current layer. The second effect is
  a decrease of the distance between the kernels moving to each other as a
  result of relaxation of magnetic tensions generated by the photospheric
  shear flows.

Title: Three-dimensional reconnection at the sun: space observations
    and collisionless models
Authors: Somov, B. V.; Kosugi, T.; Litvinenko, Y. E.; Sakao, T.;
   Masuda, S.; Oreshina, A. V.; Merenkova, E. Y.
Bibcode: 2002AdSpR..29.1035S
Altcode:
  The Yohkoh data on the site and mechanism of magnetic energy
  transformation into kinetic and thermal energies of a superhot plasma
  at the Sun require new models of reconnection under conditions of
  highlyanomalous resistivity, which are similar to that one observed in
  toroidal devices performed to study turbulent heating of a collisionless
  plasma, and its anomalous heat-conductive cooling. The models
  make intelligible the observed properties of the three-dimensional
  reconnection in solar flares.

Title: Modeling big flares: Principles and practice
Authors: Somov, B.; Kosugi, T.; Hudson, H.; Sakao, T.; Masuda, S.
Bibcode: 2002cosp...34E..43S
Altcode: 2002cosp.meetE..43S
  The basic ideas, which are under current use to model the large-scale
  solar flares, are reviewed and illustrated. The so-called `rainbow
  reconnection' model is applied to the observations of flares with
  the HXT on board Yohkoh, the MDI instrument on the SOHO, the TRACE
  satellite, and the Solar Magnetic Field Telescope (SMFT) of the
  Beijing Astronomical Observatory. This allows us to improve a theory of
  large solar flare (Somov, B., Cosmic Plasma Physics, 2000, Dordrect:
  Kluwer). In particular, the famous Bastille day 2000 flare is studied
  and interpreted. It is shown that the main large-scale structure and
  dynamics of this flare can be explained in terms of the collisionless
  3D reconnection.

Title: Collisionless Reconnection in the Structure and Dynamics of
    Active Regions
Authors: Somov, B. V.; Kosugi, T.; Litvinenko, Y. E.; Sakao, T.;
   Masuda, S.; Bogachev, S. A.; Oreshina, A. V.; Merenkova, E. Y.
Bibcode: 2001IAUS..203..558S
Altcode:
  New theoretical interpretations are discussed of the Yohkoh data on
  the site and mechanism of magnetic energy transformation into thermal
  and kinetic energies of superhot plasmas and accelerated particles. We
  develop a model that explains observed properties of reconnection in
  active regions and in flares. The transition from slow reconnection to
  fast one is demonstrated by numerical solutions of the problem taking
  into account anomalous resistivity and anomalous heat conduction. The
  model also makes intelligible the observed decrease (increase) of the
  separation between the double-footpoint hard X-ray sources in the more
  impulsive (less impulsive) flares. An accumulation of the reconnected
  magnetic flux can explain the observed ascent motion of the coronal
  source of hard X rays in flares. We demonstrate some features of
  electron and ion acceleration in collapsing magnetic traps.

Title: On the Detection of Solar Coronal High-Velocity Fields Using
    the XUV Doppler Telescope
Authors: Kobayashi, Ken; Hara, Hirohisa; Kano, Ryohei; Nagata,
   Shin'ichi; Sakao, Taro; Shimizu, Toshifumi; Tsuneta, Saku; Yoshida,
   Tsuyoshi; Harrison, Richard
Bibcode: 2000PASJ...52.1165K
Altcode:
  The XUV Doppler Telescope (XDT) is a sounding rocket experiment
  designed to detect flows in the solar corona using filter ratios. The
  XDT, successfully launched on 1998 January 31, is a normal incidence
  telescope composed of narrow-bandpass multilayer mirrors and capable
  of obtaining images 2 Å\ above and 2 Å\ below the Fe XIV 211 Å\
  (T = 1.7 MK) emission line. It has the potential to make a velocity map
  of the entire solar disk with just a few minutes of observation. The
  image ratio maps show features that translate to Doppler shifts of
  200 km s<SUP>-1</SUP> or more, including several `redshift' features
  located near footpoints of coronal loops. However, no corresponding
  velocity features were seen by the Solar and Heliospheric Observatory
  (SOHO) Coronal Diagnostic Spectrometer (CDS) in the Mg IX 368 Å (T =
  1 MK) line, suggesting that the features are not caused by Doppler
  shift. Instead, the features seem to be related to contamination
  of lower temperature (T &lt; 1 MK) emission lines and the nearby
  density-sensitive Fe XIII lines. We conclude that while no flows were
  positively identified by the XDT, this observing technique is capable
  of detecting flows of 1000 km s^{-1} independently, and 200 km s^{-1}$
  when combined with simultaneous plasma diagnostic observation.

Title: High-resolution grazing incidence telescope for the Solar-B
    observatory
Authors: Golub, Leon; DeLuca, Edward E.; Bookbinder, Jay A.; Cheimets,
   Peter; Shibasaki, Kiyoto; Sakao, Taro; Kano, Ryouhei
Bibcode: 2000SPIE.4139..313G
Altcode:
  The X-ray observations from the Yohkoh SXT provided the greatest
  step forward in our understanding of the solar corona in nearly two
  decades. We believe that the scientific objectives of the Solar-B
  mission can best be achieved with an X-ray telescope (XRT) similar to
  the SXT, but with significant improvements in spatial resolution and
  in temperature response that take into account the knowledge gained
  from Yohkoh. We present the scientific justification for this view,
  discuss the instrumental requirements that flow from the scientific
  objectives, and describe the instrumentation that will meet these
  requirements. XRT is a grazing-incidence (GI) modified Wolter I X-ray
  telescope, of 35 cm inner diameter and 2.7 m focal length. The 2048 X
  2048 back-illuminated CCD has 13.5 (mu) pixels, corresponding to 1.0
  arcsec and giving full Sun field of view. This will be the highest
  resolution GI X-ray telescope ever flown for Solar coronal studies,
  and it has been designed specifically to observe both the high and
  low temperature coronal plasma.

Title: The X-ray telescope on Solar B.
Authors: Deluca, E. E.; Golub, L.; Bookbinder, J.; Cheimets, P.;
   Shibasaki, K.; Sakao, T.; Kano, R.
Bibcode: 2000BAAS...32..827D
Altcode:
  No abstract at ADS

Title: Electron Trapping and Precipitation in Asymmetric Solar
    Flare Loops
Authors: Aschwanden, M. J.; Fletcher, L.; Sakao, T.; Kosugi, T.;
   Hudson, H.
Bibcode: 2000IAUS..195..375A
Altcode:
  Acceleration, propagation, and energy loss of particles energized in
  solar flares cannot be studied separately because their radiative
  signatures observed in the form of hard X-ray bremsstrahlung or
  radio gyrosynchrotron emission represent a convolution of all these
  processes. We analyze hard X-ray emission from solar flares using
  a kinematic model that includes free-streaming electrons (having an
  energy-dependent time-of-flight delay) as well as temporarily trapped
  electrons (which are pitch-angle scattered by Coulomb collisional
  scattering) to determine various physical parameters (trapping times,
  flux asymmetry, loss-cone angles, magnetic mirror ratios) in flare
  loops with asymmetric magnetic fields.

Title: The X-Ray Telescope on Solar B
Authors: DeLuca, E. E.; Golub, L.; Bookbinder, J.; Cheimets, P.;
   Shibasaki, K.; Sakao, T.; Kano, R.
Bibcode: 2000SPD....31Q0293D
Altcode:
  The X-ray observations from the Yohkoh SXT provided the greatest
  step forward in our understanding of the solar corona in nearly two
  decades. We believe that the scientific objectives of the Solar-B
  mission can best be achieved with an X-ray telescope (XRT) similar to
  the SXT, but with significant improvements in spatial resolution and in
  temperature response that take into account the knowledge gained from
  Yohkoh. We present the scientific justification for this view, discuss
  the instrumental requirements that flow from the scientific objectives,
  and describe the instrumentation to meet these requirements. XRT is
  a grazing-incidence (GI) modified Wolter I X-ray telescope, of 35cm
  inner diameter and 2.7m focal length. The 2048x2048 back-illuminated
  CCD has 13.5&amp;mu pixels, corresponding to 1.0 arcsec and giving
  full Sun field of view. This will be the highest resolution GI X-ray
  telescope ever flown for Solar coronal studies, and it has been designed
  specifically to observe both the high and low temperature coronal
  plasma. A small optical telescope provide visibles light images for
  coalignment with the Solar-B optical and EUV instruments. The US XRT
  team is support by a NASA Contract from MSFC.

Title: Spectral Characteristics of Above-the-Looptop Hard X-Ray Source
Authors: Masuda, S.; Sato, J.; Kosugi, T.; Sakao, T.
Bibcode: 2000AdSpR..26..493M
Altcode:
  It is observed in impulsive flares with the Hard X-ray Telescope (HXT)
  onboard Yohkoh that a hard X- ray source is located above the apex
  of a soft X-ray flaring loop in addition to double footpoint sources
  (Masuda et al. 1994, 1995). This observation suggests that the flare
  energy-release, probably magnetic reconnection, takes place not in
  the soft X-ray loop, but above the loop. It is important to derive the
  hard X-ray spectrum of this source accurately in order to understand
  how electrons are energized there. Using an improved image-synthesis
  technique with new modulation patterns (Sato 1997), we obtained hard
  X-ray images of the 13 January 1992 flare in the four HXT energy
  bands with a common photon-accumulation time. The spectrum of the
  above-the-looptop source in the energy range of 14-93 keV seems to
  be well fit by emission from an isothermal plasma whose temperature
  is about 100 MK, rather than by a non-thermal, single power-law
  spectrum. Although this is consistent with the observational result
  that the density of the ambient plasma is not high enough to stop high
  energy electrons, we need to study other events, especially intense
  events from which more accurate spectra can be derived, in order to
  confirm this result

Title: Evolution of Magnetic Field Structure and Particle Acceleration
    in Solar Flares
Authors: Sakao, T.; Kosugi, T.; Masuda, S.; Sato, J.
Bibcode: 2000AdSpR..26..497S
Altcode:
  We present hard X-ray imaging observations of impulsive solar flares
  with Yohkoh HXT, focusing on the evolution of hard X-ray double
  footpoint sources seen in the energy range above 30 keV. In 7 out
  of the 14 events studied, the separation between the double sources
  increases (at the 3σ confidence level) as the flare progresses,
  with the double sources moving nearly anti-parallel to each other
  in most cases. Implications of these results to the global magnetic
  field structure responsible for solar flare energy release / particle
  acceleration are discussed

Title: Improvement of Yohkoh HXT Imaging and an Analysis of the 1997
    November 6, X9 Flare
Authors: Sato, J.; Masuda, S.; Kosugi, T.; Sakao, T.
Bibcode: 2000AdSpR..26..501S
Altcode:
  The imaging capability of the Hard X-ray Telescope (HXT) on board
  Yohkoh has been drastically improved by (1) adopting new instrumental
  response functions (modulation patterns) derived from a self-calibration
  procedure that makes use of solar flares themselves as calibration
  sources, (2) revising the Maximum Entropy (MEM) image synthesis
  procedure for better total flux estimation, and (3) incorporating in
  MEM properly estimated observation errors. One of the most intense
  flares so far observed with HXT, the 1997 November 6, X9 flare, has
  been analyzed with the new HXT imaging program. Two footpoint sources
  are clearly seen and show systematic motions during the impulsive
  phase. This may provide a new clue to understand the coronal magnetic
  field structure involved in the energy release process of flares

Title: Basic Physics of Collisionless Three-Dimensional Reconnection
    in the Solar Corona Related to Yohkoh Observations
Authors: Somov, B. V.; Kosugi, T.; Masuda, S.; Sakao, T.
Bibcode: 2000AdSpR..25.1821S
Altcode:
  New results concerning magnetic reconnection in the solar corona
  are reviewed. We apply the collisionless 3D reconnection theory -
  more exactly, the model of a high-temperature turbulent-current
  non-neutral current sheet - to the coronal conditions derived from the
  observations with the HXT and SXT onboard Yohkoh. New interpretations
  are discussed of the Yohkoh data on the site and mechanism of magnetic
  energy transformation into kinetic and thermal energies of superhot
  plasmas and accelerated high-energy particles. Open issues are the
  focus of our attention

Title: Initial Results from the XUV Doppler Telescope
Authors: Kano, R.; Hara, H.; Kobayashi, K.; Kumagai, K.; Nagata, S.;
   Sakao, T.; Shimizu, T.; Tsuneta, S.; Yoshida, T.
Bibcode: 2000AdSpR..25.1739K
Altcode:
  We developed a unique telescope to obtain simultaneous XUV images and
  the velocity maps by measuring the line-of-sight Doppler shifts of the
  Fe XIV 211A&amp;ring line (T = 1.8 MK): the Solar XUV Doppler Telescope
  (hereafter XDT). The telescope was launched by the Institute of Space
  and Astronautical Science with the 22nd S520 rocket on January 31,
  1998, and took 14 XUV whole sun images during 5 minutes. Simultaneous
  observations of XDT with Yohkoh (SXT), SOHO (EIT, CDS, LASCO and MDI)
  were successfully carried out. The images taken with EIT, XDT and SXT
  are able to cover the wide temperature ranging from 1 to 10 MK, and
  clearly show the multi-temperature nature of the solar corona. Indeed,
  we notice that both the cool (1-2 MK) loops observed with EIT and
  XDT, and the hot (&gt;3 MK) loops observed with SXT exist in the same
  active regions but in a spatially exclusive way. The XDT red-blue ratio
  between longer- and shorter-wavelength bands of Fe XIV 211A&amp;ring
  line indicates a possible down-flow of 1.8 MK plasma near the footpoints
  of multiple cool loops

Title: Three-dimensional Reconnection in the Solar Corona Related
    to Yohkoh Observations
Authors: Somov, B. V.; Merenkova, E. Yu.; Kosugi, T.; Sakao, T.;
   Masuda, S.; Oreshina, A. V.
Bibcode: 1999ESASP.448..883S
Altcode: 1999mfsp.conf..883S; 1999ESPM....9..883S
  No abstract at ADS

Title: HXT Observations of Solar Flares - A Review and Perspective -
Authors: Sakao, T.
Bibcode: 1999spro.proc..321S
Altcode:
  We present hard X-ray imaging observations of impulsive solar flares
  made with the Hard X-ray Telescope (HXT) aboard the Yohkoh satellite,
  and emphasise the magnetic field structure and its evolution during
  flares. The HXT has revealed that the bulk of hard X-rays above
  30 keV is emitted from the footpoints of a flaring magnetic loop
  by electrons accelerated near the loop top. This implies that the
  evolution of hard X-ray footpoints reflects that of magnetic field
  structure responsible for the energy release, through which we can
  infer the magnetic field structure itself. We review progress so far
  made along these lines, including the relationship between magnetic
  field structure and thermal/non-thermal aspects of impulsive flares,
  followed by discussion of the (three-dimensional) magnetic field
  structure inferred from motions of individual footpoints. We also
  discuss, from a viewpoint of magnetic field structure, near-future
  perspective of hard X-ray solar physics.

Title: Coronal Hard X-rays in Solar Flares: Yohkoh Observations
    and Interpretation
Authors: Somov, B. V.; Litvinenko, Y. E.; Kosugi, T.; Sakao, T.;
   Masuda, S.; Bogachev, S. A.
Bibcode: 1999ESASP.448..701S
Altcode: 1999ESPM....9..701S; 1999mfsp.conf..701S
  No abstract at ADS

Title: Narrow-Bandpass Multilayer Mirrors for an Extreme-Ultraviolet
    Doppler Telescope
Authors: Hara, Hirohisa; Nagata, Shin'ichi; Kano, Ryouhei; Kumagai,
   Kazuyoshi; Sakao, Taro; Shimizu, Toshifumi; Tsuneta, Saku; Yoshida,
   Tsuyoshi; Ishiyama, Wakana; Oshino, Tetsuya; Murakami, Katsuhiko
Bibcode: 1999ApOpt..38.6617H
Altcode:
  No abstract at ADS

Title: The XUV Doppler Telescope (XDT)
Authors: Sakao, T.; Tsuneta, S.; Hara, H.; Shimizu, T.; Kano, R.;
   Kumagai, K.; Yoshida, T.; Nagata, S.; Kobayashi, K.
Bibcode: 1999SoPh..187..303S
Altcode:
  We present an overview and instrumental details of the solar XUV Doppler
  Telescope (XDT) launched in January 1998 with the S520CN-22 sounding
  rocket of the Institute of Space and Astronautical Science. The XDT
  observes nearly single-temperature solar corona at 1.8 MK with angular
  resolution of ≈ 5'' pixel size, together with the ability to detect
  the coronal velocity field with a full-Sun field of view. By use of
  normal incidence optics whose primary and secondary mirrors are coated
  with multilayer materials in two sectors, the XDT takes images of the
  Sun in a set of shorter and longer wavelength bands around the Fe xiv
  211.3 Å emission line. Summation of a pair of images in the two bands
  provides an image of the 1.8 MK-corona while the difference between
  the two provides velocity images of the Fe xiv-emitting plasma. A brief
  description on the observation sequence together with the flight result
  is also given.

Title: Deconvolution of Directly Precipitating and Trap-precipitating
    Electrons in Solar Flare Hard X-Rays. III.Yohkoh Hard X-Ray Telescope
    Data Analysis
Authors: Aschwanden, Markus J.; Fletcher, Lyndsay; Sakao, Taro;
   Kosugi, Takeo; Hudson, Hugh
Bibcode: 1999ApJ...517..977A
Altcode:
  We analyze the footpoint separation d and flux asymmetry A of
  magnetically conjugate double footpoint sources in hard X-ray images
  from the Yohkoh Hard X-Ray Telescope (HXT). The data set of 54 solar
  flares includes all events simultaneously observed with the Compton
  Gamma Ray Observatory (CGRO) in high time resolution mode. From the CGRO
  data we deconvolved the direct-precipitation and trap-precipitation
  components previously (in Paper II). Using the combined measurements
  from CGRO and HXT, we develop an asymmetric trap model that allows
  us to quantify the relative fractions of four different electron
  components, i.e., the ratios of direct-precipitating (q<SUB>P1</SUB>,
  q<SUB>P2</SUB>) and trap-precipitating electrons (q<SUB>T1</SUB>,
  q<SUB>T2</SUB>) at both magnetically conjugate footpoints. We find mean
  ratios of q<SUB>P1</SUB>=0.14+/-0.06, q<SUB>P2</SUB>=0.26+/-0.10,
  and q<SUB>T</SUB>=q<SUB>T1</SUB>+q<SUB>T2</SUB>=0.60+/-0.13. We
  assume an isotropic pitch-angle distribution at the
  acceleration site and double-sided trap precipitation
  (q<SUB>T2</SUB>/q<SUB>T1</SUB>=q<SUB>P2</SUB>/q<SUB>P1</SUB>)
  to determine the conjugate loss-cone angles
  (α<SUB>1</SUB>=42<SUP>deg</SUP>+/-11<SUP>deg</SUP> and
  α<SUB>2</SUB>=52<SUP>deg</SUP>+/-10<SUP>deg</SUP>) and magnetic
  mirror ratiosat both footpoints (R<SUB>1</SUB>=1.6,...,4.0 and
  R<SUB>2</SUB>=1.3,...,2.5). From the relative displacement of
  footpoint sources we also measure altitude differences of hard
  X-ray emission at different energies, which are found to decrease
  systematically with higher energies, with a statistical height
  difference of h<SUB>Lo</SUB>-h<SUB>M1</SUB>=980+/-250 km and
  h<SUB>M1</SUB>-h<SUB>M2</SUB>=310+/-300 km between the three lower
  HXT energy channels (Lo, M1, M2).

Title: Development and flight performance of tip-tilt mirror system
    for a sounding rocket observation of the Sun.
Authors: Shimizu, T.; Yoshida, T.; Tsuneta, S.; Sakao, T.; Kano,
   R.; Hara, H.; Nagata, S.; Kodeki, K.; Inoue, M.; Fukushima, K.;
   Kashiwase, T.
Bibcode: 1999RNAOJ...4...43S
Altcode: 1999RNOAJ...4...43S
  A tip-tilt mirror (TTM) system was developed for the XUV Doppler
  telescope (XDT) on board an ISAS sounding rocket. The spatial resolution
  of the telescope is about 5″ whereas the pointing stability is
  only ±0.3° with the rocket pointing control system. To achieve
  better than 5″stability on the focal plane of the telescope, the
  TTM system controls the tilt of the secondary mirror with fixed-coil
  magnetic actuators. The control signal to stabilize focal-plane images
  is supplied by the position-sensitive detector (PSD) of a pin-hole
  telescope equipped inside XDT. Closed-loop controls are made with
  the on-board software on the DSP processor. The sounding rocket was
  successfully launched on 31 January 1998 from the Kagoshima Space
  Center of ISAS. TTM worked perfectly during the flight, and achieved
  better than 5″stability on the focal plane during CCD exposures.

Title: Multi-wavelength observations of POST flare loops in two long
    duration solar flares
Authors: Harra-Murnion, L. K.; Schmieder, B.; van Driel-Gesztelyi,
   L.; Sato, J.; Plunkett, S. P.; Rudawy, P.; Rompolt, B.; Akioka, M.;
   Sakao, T.; Ichimoto, K.
Bibcode: 1998A&A...337..911H
Altcode:
  We have analysed two Long Duration solar Events (LDEs) which produced
  large systems of Post Flare Loops (PFLs) and which have been observed by
  Yohkoh and ground-based observatories. Using the Maximum Entropy Method
  (MEM) image synthesis technique with new modulation patterns we were
  able to make hard X-ray (HXR) images of the post flare loops recorded
  in the L Channel (13.9-22.7 keV) of the Yohkoh Hard X-ray Telescope. We
  obtained co-aligned 2-D maps in Hα (10(4) K), in soft X-rays (5x 10(6)
  K) and in hard X-rays (20x 10(6) K). We conclude that the soft X-ray
  (SXR) loops lie higher than the Hα loops and the former are overlaid
  by HXR emission. This is suggestive of the magnetic reconnection
  process. However some details are not consistent with the standard
  models. Firstly the separation between the HXR source and the SXR
  loop increases with time, with the HXR source being approximately
  a factor of five larger than the equivalent source in impulsive
  flares. Secondly the cooling times deduced from observations are longer
  than the theoretically expected ones and the discrepancy increases
  with time. We review the current models in view of these results.

Title: Development of the tip-tilt mirror system for the solar
    XUV telescope
Authors: Kodeki, Kazuhide; Fukushima, Kazuhiko; Kashiwase, Toshio;
   Inoue, Masao; Shimizu, Toshifumi; Yoshida, Tsuyoshi; Sakao, Taro;
   Hara, Hirohisa; Nagata, Shin'ichi; Kano, Ryouhei; Tsuneta, Saku
Bibcode: 1998SPIE.3356..922K
Altcode:
  This paper describes the design and prelaunch performance of the
  tip-tilt mirror (TTM) system developed for the XUV Cassegrain telescope
  aboard the ISAS sounding rocket experiment. The spatial resolution
  of the telescope is about 5 arcsec, whereas the rocket pointing is
  only controlled to be within +/- 0.5 degree around the target without
  stability control. The TTM is utilized to stabilize the XUV image
  on the focal planes by tilting the secondary mirror with two-axes
  fixed-coil type actuators. The two position- sensitive detectors in
  the telescope optics and in the TTM mechanical structure from the
  normal and local closed-loop modes. The TTM has four grain modes with
  automatic transition among the modes. The low gain mode is used in
  the initial acquisition, and in case the TTM loses the tracking. The
  high gain mode is used in the normal tracking mode. This arrangement
  provides us with the wide initial acquisition angle with single TTM
  system as well as the high pointing accuracy once the tracking is
  established. The TTM has a launch-lock mechanism against the launch
  vibration of 16G. The closed-loop control with command and telemetry
  interface is done by the flight software against the launch vibration
  of 16G. The closed-loop control with command and telemetry interface
  is done by the flight software on the DSP processor. The use of the
  fast processor brings in the significant reduction in the weight and
  size of the control- electronics, more flexible control system, and
  shorter design and testing period.

Title: Collisionless Three-dimensional Reconnection In Impulsive
    Solar Flares
Authors: Somov, Boris V.; Kosugi, Takeo; Sakao, Taro
Bibcode: 1998ApJ...497..943S
Altcode:
  Two subclasses of impulsive solar flares, observed with the Hard X-Ray
  Telescope (HXT) onboard Yohkoh, have been discovered by Sakao et al. The
  two subclasses can be characterized as more impulsive (MI) and less
  impulsive (LI) flares, the former having a shorter total duration of
  the impulsive phase in the hard X-ray emission than the latter. We
  assume that in both subclasses, the collisionless three-dimensional
  reconnection process occurs at the separator with a longitudinal
  magnetic field. The high-temperature turbulent-current sheet (HTTCS),
  located along the separator, generates accelerated particles and fast
  outflows of ``superhot'' (T &gt;= 30 MK) plasma. Powerful anomalous
  heat-conductive fluxes along the reconnected field lines maintain a high
  temperature in the superhot plasma. <P />The difference between the LI
  and MI flares presumably appears because the footpoint separation (the
  distance between two brightest hard X-ray sources) increases in time in
  the LI flares, but decreases in the MI flares. According to our model,
  in the LI flares the three-dimensional reconnection process accompanies
  an increase in the longitudinal magnetic field at the separator. In
  contrast, in the MI flares the reconnection proceeds with a decrease
  of the longitudinal field; hence, the reconnection rate is higher
  in the MI flares. <P />Since reconnection in the MI flares proceeds
  with a decrease of the longitudinal field, the reconnected field lines
  become shorter in this process. As the reconnected lines become shorter,
  accelerated electron beams arrive at the upper chromosphere faster. So,
  in the MI flares chromospheric evaporation begins earlier than in the
  LI flares. The evaporation process driven by accelerated electron beams
  generates upflows of ``warm'' (T &lt;= 10 MK) plasma that interacts
  with downflows of superhot plasma and can switch off the accumulation of
  superhot plasma in the MI flares during the impulsive phase. In the LI
  flares, however, an observable amount of superhot plasma is accumulated
  even during the impulsive phase. Moreover, since the cooling timescales
  increase with the length of the reconnected field lines, our argument
  for the association of superhot plasma with longer lines may remain
  valid to a reasonable extent even if the chromospheric evaporated
  plasma mixes with the reconnected outflow and superhot temperatures are
  reached in this mixture. Further analysis of the Yohkoh data obtained
  simultaneously with the Hard and Soft X-Ray Telescopes and the bent
  crystal spectrometer (BCS) is necessary to distinguish the superhot
  components of chromospheric and coronal origins in different classes
  of flares as well as at different phases of their development.

Title: XUV Doppler Telescope Aboard Sounding Rocket
Authors: Yoshida, T.; Kano, R.; Nagata, S.; Hara, H.; Sakao, T.;
   Shimizu, T.; Tsuneta, S.
Bibcode: 1998ASSL..229..383Y
Altcode: 1998opaf.conf..383Y
  No abstract at ADS

Title: Energy Release and Particle Acceleration in Solar Flares with
    Respect to Flaring Magnetic Loops
Authors: Sakao, T.; Kosugi, T.; Masuda, S.
Bibcode: 1998ASSL..229..273S
Altcode: 1998opaf.conf..273S
  No abstract at ADS

Title: Summary of Coronal Hard X-Ray Sources Observed with Yohkoh/hxt
Authors: Masuda, S.; Kosugi, T.; Sakao, T.; Sato, J.
Bibcode: 1998ASSL..229..259M
Altcode: 1998opaf.conf..259M
  No abstract at ADS

Title: XUV Doppler telescope with multilayer optics
Authors: Hara, Hirohisa; Kano, Ryouhei; Nagata, Shin'ichi; Sakao, Taro;
   Shimizu, Toshifumi; Tsuneta, Saku; Yoshida, Tsuyoshi; Kosugi, Takeo
Bibcode: 1997SPIE.3113..420H
Altcode:
  We present an overview of a sounding-rocket experiment, which is
  scheduled to be launched by the Institute of Space and Astronautical
  Science (ISAS) in January 1998, the rising phase of the 11-year activity
  cycle of the sun. The purpose of this experiment is (1) to obtain
  whole-sun images taken in an XUV emission line, Fe XIV 211 angstrom,
  using the normal incidence multilayer optics with a high spectral
  resolution of (lambda) /(Delta) (lambda) approximately equals 40, and
  (2) to carry out the velocity-field measurement with detection limit
  as high as 100 km/s.

Title: Development of multilayer mirrors for the XUV Doppler telescope
Authors: Nagata, Shin'ichi; Hara, Hirohisa; Sakao, Taro; Shimizu,
   Toshifumi; Tsuneta, Saku; Yoshida, Tsuyoshi; Ishiyama, Wakana;
   Murakami, Katsuhiko; Oshino, Tetsuya
Bibcode: 1997SPIE.3113..193N
Altcode:
  We present the development status of the normal incidence XUV multilayer
  mirrors for XUV Doppler telescope, which observes coronal velocity
  fields of the whole sun. The telescope has two narrow band-pass
  multilayer mirrors tuned to slightly longer and shorter wavelengths
  around the Fe XIV line at 211.3 Angstrom. From the intensity difference
  of the images taken with these two bands, we can obtain Dopplergram of
  1.8 MK plasma of the whole sun. It is required that the multilayer has
  high wavelength-resolution ((lambda) /(Delta) (lambda) approximately
  30 per mirror), anti-reflection coating for intense He II 304 angstrom
  emission line and high d-spacing uniformity of approximately 1%.

Title: Hard X-ray Footpoints and Soft X-ray Loops in Solar Flares
Authors: Masuda, S.; Sakao, T.; Kosugi, T.; Sato, J.
Bibcode: 1997SPD....28.0170M
Altcode: 1997BAAS...29..892M
  Yohkoh Hard X-ray Telescope (HXT) found, in the impulsive phase of
  solar flares, a compact hard X-ray (HXR) source located above the
  corresponding soft X-ray (SXR) loop apex observed with Yohkoh Soft
  X-ray Telescope (SXT). This observation suggests that the flare primary
  energy release takes place above (outside of) the bright SXR loop, and
  that magnetic reconnection is responsible for the energy release. One
  possible interpretation is that electrons are energized in or near the
  ``above-the-loop-top'' HXR source where reconnection outflow impinges
  the underlying loop and forms a fast MHD shock. The energized electrons
  stream down along magnetic field lines to the footpoints (``double
  footpoint HXR sources'') of a newly reconnected loop. This implies
  that the footpoint HXR sources must be located further from the loop
  center than the two ends of the loop found via SXR because reconnection
  starts from innermost magnetic fields reaching the outermost ones later
  and also because it takes a few minutes for the newly reconnected
  loop to be filled with hot plasma and become bright in SXRs. Under
  such a motivation, we have compared HXR images in the HXT M1-band a
  (23-33 keV) with SXR images taken simultaneously with the SXT Be
  filter. In this analysis, the center of each HXR footpoint source
  represents the position of that source. For each SXR loop, first we
  remove the low-intensity part (&lt; 1/10 of the maximum brightness)
  then the two ends of the remaining loop emission are taken to represent
  the positions of the SXR footpoints. In seven out of the eleven cases
  analyzed, we find that the footpoint HXR sources are located outside
  the corresponding SXR loop footpoints. The distance between the HXR
  sources is a little longer than that between the SXR loop footpoints,
  on average, by ~ 0.9 +/- 1.5 arcsec. Although this result seems to be
  consistent with the scenario mentioned above, this difference is not
  significantly large. A further study is in progress.

Title: Principles, Practical Problems, and the Performance of MEM
    Imaging for the YOHKOH Hard X-ray Telescope
Authors: Kosugi, Takeo; Sato, Jun; Sakao, Taro; Masuda, Satoshi
Bibcode: 1997SPD....28.1301K
Altcode: 1997BAAS...29R.916K
  The Hard X-ray Telescope (HXT) on-board Yohkoh is a Fourier-synthesis
  telescope with 64 modulation collimators. Solar flare images have been
  synthesized using the Maximum Entropy Method (MEM) or some other imaging
  techniques from sets of the 64 photon counts. This paper reports our
  recent success in improving the MEM imaging for HXT. The key factors
  that led us to this success are as follows. First, modulation patterns
  for the 64 individual collimators were precisely re-calibrated in orbit
  using solar flares themselves as calibration sources. Note that the
  patterns we had used before were based on the pre-launch calibrations
  using artificial sources. Also the formulae that represent the patterns
  are renewed. Second, we re-formulated the MEM principle; now the total
  flux is a free parameter to be determined by the MEM principle. This new
  formulation was successfully incorporated into an iterative code. Third,
  the observation error terms were estimated and incorporated properly in
  the MEM imaging. With these improvements, we have confirmed (i) that the
  so-called over-resolution problem, sometimes misunderstood as resulting
  from the MEM principle itself, disappears so that the stability of
  images improves drastically, (ii) that the image quality improves
  proportionally with increasing photon counts as naturally expected,
  (iii) that the number of events for which MEM imaging fails decreases
  (with a small number of exceptions, maybe due to large intrinsic source
  size), and (iv) that the similarity between HXT L-band images and SXT
  images becomes much clearer than before.

Title: The Solar Flare of 1992 August 17 23:58 UT} %
Authors: Takahashi, Masaaki; Watanabe, Tetsuya; Sakai, Jun-Ichi;
   Sakao, Taro; Kosugi, Takeo; Sakurai, Takashi; Enome, Shinzo; Hudson,
   Hugh S.; Hashimoto, Shizuyo; Nitta, Nariaki
Bibcode: 1996PASJ...48..857T
Altcode:
  A small flare (C4.3 in the GOES X-ray class) was well observed by
  all of the instruments on board Yohkoh. The X-ray light curves have
  double peaks which are about 5 min apart. Until the first peak from
  flare onset, four compact areas brighten up in the soft X-ray region,
  which are aligned almost on one straight line. We regard them as being
  footpoints of two sets of loops, which are identifiable in soft X-ray
  images, since their locations match those of hard X-ray sources. Indeed,
  after the second peak, the temporal behavior of the temperature and
  emission measure at each point is consistent with the existence of
  two such loops. Comparing our results with recent MHD simulations,
  we propose a possible scenario for this flare that is based on the
  coalescence of two loops.

Title: Japanese sounding rocket experiment with the solar XUV
    Doppler telescope
Authors: Sakao, Taro; Tsuneta, Saku; Hara, Hirohisa; Kano, Ryouhei;
   Yoshida, Tsuyoshi; Nagata, Shin'ichi; Shimizu, Toshifumi; Kosugi,
   Takeo; Murakami, Katsuhiko; Wasa, Wakuna; Inoue, Masao; Miura,
   Katsuhiro; Taguchi, Koji; Tanimoto, Kazuo
Bibcode: 1996SPIE.2804..153S
Altcode:
  We present an overview of an ongoing Japanese sounding rocket project
  with the Solar XUV Doppler telescope. The telescope employs a pair
  of normal incidence multilayer mirrors and a back-thinned CCD, and is
  designed to observe coronal velocity field of the whole sun by measuring
  line- of-sight Doppler shifts of the Fe XIV 211 angstroms line. The
  velocity detection limit is estimated to be better than 100 km/s. The
  telescope will be launched by the Institute of Space and Astronautical
  Science in 1998, when the solar activity is going to be increasing
  towards the cycle 23 activity maximum. Together with the overview of
  the telescope, the current status of the development of each telescope
  components including multilayer mirrors, telescope structure, image
  stabilization mechanism, and focal plane assembly, are reviewed. The
  observation sequence during the flight is also briefly described.

Title: Hard and Soft X-Ray Observations of Solar Limb Flares
Authors: Mariska, John T.; Sakao, T.; Bentley, R. D.
Bibcode: 1996ApJ...459..815M
Altcode:
  Using observations from the Yohkoh Bragg Crystal Spectrometer, hard
  X-ray telescope, and soft X-ray telescope, we have examined eight limb
  flares. Four of the flares have the footpoints occulted by the solar
  limb. We find that the occulted flares generally have softer hard
  X-ray spectra and smaller peak values of the nonthermal broadening
  velocity than nonocculted flares. All other physical parameters show
  no differences between occulted flares and nonocculted flares. The
  hard X-ray spectra support a model in which the footpoint emission
  is due to thick-target sources, while the looptop emission is due to
  thin-target sources. High spectral resolution hard X-ray observations
  should thus show a break in the hard X-ray spectrum of the looptop
  source. We can find no obvious explanation for the differences in
  nonthermal broadening velocity.

Title: Soft X-Ray Flare Dynamics
Authors: Doschek, G. A.; Mariska, John T.; Sakao, T.
Bibcode: 1996ApJ...459..823D
Altcode:
  We discuss the dynamics of four soft X-ray flares as revealed by the
  X-ray resonance line profiles of the He-like ions, Fe xxv, Ca xix,
  and S xv. The flares chosen for analysis belong to a subclass of
  events that have intense Doppler blueshifted spectral signatures
  during the rise phase. The spectra were obtained froin the Bragg
  crystal spectrometer (BC S) experiment flown on the Japanese Yohkoh
  spacecraft. We deconvolve the line profiles into a flare decay phase
  component (stationary component) produced by nonmoving plasma with
  little or no turbulent motions, and a flare rise phase component
  (dynamic component) produced by bulk plasma motion and turbulence. The
  dynamic component is further deconvolved into a high-speed component
  (greater than 400 km s <SUP>1</SUP>) and a lower speed, more turbulent
  component. We find that the dynamic and stationary components have
  approximately the same electron temperature. The dynamic and stationary
  component fluxes are compared with hard X-ray fluxes obtained from the
  hard X-ray telescope (HXT) on Yohkoh We find that the onset time of
  the high-speed dynamic component corresponds closely to the onset of
  hard X-rays. We discuss the X-ray morphology of the flares as revealed
  by the soft X-ray telescope (SXT) and hard X-ray telescope (HXT) on
  Yohkoh. From analysis of the X-ray light curves of individual pixels in
  the SXT images, we believe we have been able to determine at least some
  of the locations of the dynamic component in the images. Although the
  observations support many aspects of chromospheric evaporation models,
  there are significant problems. No obvious rising fronts of plasma
  are observed for any of the flares. There are apparent footpoint hard
  X-ray sources that cannot be physically related in an obvious manner
  with the main sources of soft X-ray emission. The flares are complex,
  and therefore there are some ambiguities in interpretation of the
  morphology.

Title: Characteristics of hard X-ray double sources in impulsive
    solar flares
Authors: Sakao, T.; Kosugi, T.; Masuda, S.; Yaji, K.; Inda-Koide,
   M.; Makishima, K.
Bibcode: 1996AdSpR..17d..67S
Altcode: 1996AdSpR..17...67S
  Imaging observations of solar flare hard X-ray sources with the Hard
  X-ray Telescope aboard theYohkoh satellite have revealed that hard
  X-ray emissions (&gt; 30 keV) originate most frequently from double
  sources. The double sources are located on both sides of the magnetic
  neutral line, suggesting that the bulk of hard X-rays is emitted
  from footpoints of flaring magnetic loops. We also found that hard
  X-rays from the double sources are emitted simultaneously within a
  fraction of second and that the weaker source tends to be located in
  the stronger magnetic field region, showing a softer spectrum. Physical
  implications on the observed characteristics of the hard X-ray double
  sources are discussed.

Title: YOHKOH observations of solar limb flares
Authors: Bentley, R. D.; Mariska, J. T.; Sakao, T.
Bibcode: 1996ASPC..109..107B
Altcode: 1996csss....9..107B
  No abstract at ADS

Title: Hard and Soft X-ray Images of an LDE Flare
Authors: Sato, J.; Kosugi, T.; Sakao, T.
Bibcode: 1996mpsa.conf..545S
Altcode: 1996IAUCo.153..545S
  No abstract at ADS

Title: Loop-Top Hard X-ray Source in Solar Flares
Authors: Masuda, S.; Kosugi, T.; Shibata, K.; Hara, H.; Sakao, T.
Bibcode: 1996mpsa.conf..203M
Altcode: 1996IAUCo.153..203M
  No abstract at ADS

Title: Imaging Spectra of Hard X-ray from the Footpoints of Solar
    Impulsive Loop Flares
Authors: Takakura, T.; Kosugi, T.; Sakao, T.; Makishima, K.;
   Inda-Koide, M.; Masuda, S.
Bibcode: 1996mpsa.conf..541T
Altcode: 1996IAUCo.153..541T
  No abstract at ADS

Title: The Weak Blue Bump of H2106-099 and Active Galactic Nuclei
    Dereddening
Authors: Grossan, B.; Remillard, R. A.; Bradt, H. V.; Brissenden,
   R. J.; Ohashi, T.; Sakao, T.
Bibcode: 1996ApJ...457..199G
Altcode: 1996astro.ph.11173G
  We present multifrequency spectra of the Seyfert 1 galaxy H2106-099,
  from radio to hard X-rays, spanning over a decade of observations. The
  hard X-ray (2-20 keV) spectrum measured with Ginga was not unusual,
  with a log slope (F<SUB>υ</SUB> ∝ E<SUP>α</SUP>), of -0.80±0.02
  on 1988 May 18 and -1.02±0.10 on 1988 May 22/23 UT, and with no
  significant observed variations in total flux. Other measurements
  showed variability and unusual spectral features: The V band flux
  was observed to change by a factor of 1.8 (&gt;10 σ)in 6 weeks. Only
  moderate optical Fe II emission is present, but strong [Fe VII] and [Fe
  X] epochs. The Balmer lines show greater than 25% variations in flux
  relative to the mean, and He I changed by more than 100% relative to
  the mean in 6 yr. The most surprising finds came from the composite UV
  through near-IR spectrum: If the spectrum is dereddened by the galactic
  extinction value derived from 21 cm observations, a residual 2175 Å
  absorption feature is present. Additional dereddening to correct the
  feature yields E(B - V) = 0.07 mag due to material outside our Galaxy,
  most probably associated with the active galactic nucleus (AGN) or its
  host galaxy. No other clear indications of reddening are observed in
  this object, suggesting that blue bump strength measurements in low
  and intermediate redshift AGNs could be incorrect if derived without
  UV observations of the region near 2175 A in the AGN frame. After
  all reddening corrections are performed, the log slope of H2106 -099
  from the near-IR (∼12500 Å) to the UV (∼1400 Å), -0.94±0.05,
  is steep compared to other AGNs, suggesting that the blue bump in
  this object is intrinsically weak. Weak blue bumps are, therefore,
  not always an artifact caused by reddening. The spectral indices of
  this object in the optical-UV region are steeper than those predicted
  by optically thin free-free emission models; therefore, some other
  mechanism must dominate the continuum in this region.

Title: Hard and Soft X-ray Observations of Solar Limb Flares
Authors: Mariska, J. T.; Sakao, T.; Bentley, R. D.
Bibcode: 1996mpsa.conf..523M
Altcode: 1996IAUCo.153..523M
  No abstract at ADS

Title: Non-Thermal Processes and Superhot Plasma Creation in Solar
    Flares
Authors: Sakao, T.; Kosugi, T.
Bibcode: 1996mpsa.conf..169S
Altcode: 1996IAUCo.153..169S
  No abstract at ADS

Title: Coordinated OVRO, BATSE, Yohkoh, and BBSO Observations of
    the 1992 June 25 M1.4 Flare
Authors: Wang, H.; Gary, D. E.; Zirin, H.; Schwartz, R. A.; Sakao,
   T.; Kosugi, T.; Shibata, K.
Bibcode: 1995ApJ...453..505W
Altcode:
  We compare 1-14 GHz microwave images observed at the Owens Valley Radio
  Observatory (OVRO), 16- and 256-channel hard X-ray spectra obtained by
  the Burst and Transient Source Experiment (BATSE) onboard the Compton
  Gamma Ray Observatory (CGRO), soft and and hard X-ray images obtained
  by Yohkoh, and Hα images and magnetograms observed at the Big Bear
  Solar Observatory (BBSO) for the 1992 June 25 M1.4 flare. We find the
  following unique properties for this flare: (1) Soft X-ray emissions
  connect two foot- points, the primary microwave source is located at
  one footpoint, and hard X-ray emissions are concentrated in the other
  footpoint The radio footpoint is associated with an umbra and may
  have stronger magnetic field. (2) During the period that 256-channel
  BATSE data are available, the hard X-ray photon spectrum consists
  of two components: a superhot component with a temperature of 8.4
  × 10<SUP>7</SUP> K and emission measure of 2.5 × 10<SUP>46</SUP>
  cm<SUP>-3</SUP> and a power-law component with a photon index of
  4.2. This is the first time that such a high temperature is reported
  for the hard X-ray thermal components. It is even more interesting
  that such a superhot component is identified before the peak of the
  flare. The microwave brightness temperature spectra during the same
  period also demonstrate two components: a thermal component near the
  loop top and a nonthermal component at the footpoint of the loop. The
  microwave thermal component has the similar temperature as that of
  the hard X-ray superhot component. These measurements are consistent
  with the theory that the microwaves and hard X-rays are due to the
  same group of electrons, despite the fact that they are separated by
  35,000 km. (3) The soft X-ray emissions brighten the existing loops and
  co-align with Hα emissions throughout the entire duration of the flare.

Title: Microwave and Hard X-Ray Observations of Footpoint Emission
    from Solar Flares
Authors: Kundu, M. R.; Nitta, N.; White, S. M.; Shibasaki, K.; Enome,
   S.; Sakao, T.; Kosugi, T.; Sakurai, T.
Bibcode: 1995ApJ...454..522K
Altcode:
  We investigate radio and X-ray imaging data for two solar flares in
  order to test the idea that asymmetric precipitation of nonthermal
  electrons at the two ends of a magnetic loop is consistent with the
  magnetic mirroring explanation. The events we present were observed in
  1993 May by the HXT and SXT X-ray telescopes on the Yohkoh spacecraft
  and by the Nobeyama 17 GHz radioheliograph. The hard X-ray images in
  one case show two well-separated sources; the radio images indicate
  circularly polarized, nonthermal radio emission with opposite polarities
  from these two sources, indicating oppositely directed fields and
  consistent with a single-loop model. In the second event there are
  several sources in the HXT images which appear to be connected by
  soft X-ray loops. The strongest hard X-ray source has unpolarized
  radio emission, whereas the strongest radio emission lies over strong
  magnetic fields and is polarized. In both events the strongest radio
  emission is highly polarized and not coincident with the strongest
  hard X-ray emission. This is consistent with asymmetric loops in
  which the bulk of the precipitation (and hence the X-ray emission)
  occurs at the weaker field footpoint.

Title: Hard X-Ray Sources and the Primary Energy-Release Site in
    Solar Flares
Authors: Masuda, Satoshi; Kosugi, Takeo; Hara, Hirohisa; Sakao, Taro;
   Shibata, Kazunari; Tsuneta, Saku
Bibcode: 1995PASJ...47..677M
Altcode:
  Accurately coaligned hard and soft X-ray images, taken simultaneously
  with the Hard X-ray Telescope (HXT) and the Soft X-ray Telescope
  (SXT) aboard Yohkoh, of impulsive solar flares on 1992 January 13
  (17:29 UT), 1992 October 4 (22:21 UT), and 1993 February 17 (10:35
  UT), occurring near the limb, clearly reveal that, in addition to
  double-footpoint sources, a hard X-ray source exists well above the
  corresponding soft X-ray loop structure around the peak time of the
  impulsive phase. This hard X-ray source shows an intensity variation
  similar to double-footpoint sources and a spectrum that is relatively
  hard compared with that of loop-top gradual source which appeared later
  in the flare. We believe that this is the first clear evidence that
  magnetic reconnection, which is responsible for the primary flare energy
  release, is under progress above the soft X-ray flaring loop. Maybe
  this ``loop-top'' hard X-ray source represents the reconnection site
  itself or the site where the downward plasma stream, ejected from
  the reconnection point far above the hard X-ray source, collides with
  the underlying closed magnetic loop. The characteristics of this hard
  X-ray source are quantitatively discussed in the schemes of thermal
  (T &gt;~ 10(8) K) and nonthermal interpretations of hard X-ray emission.

Title: YOHKOH SXT/HXT Observations of a Two-Loop Interaction Solar
    Flare on 1992 December 9
Authors: Inda-Koide, Mika; Sakai, Jun-Ichi; Koide, Shinji; Kosugi,
   Takeo; Sakao, Taro; Shimizu, Toshifumi
Bibcode: 1995PASJ...47..323I
Altcode:
  Observations with the Soft X-ray and Hard X-ray Telescopes aboard Yohkoh
  of a simple solar flare on 1992 December 9 are discussed. The soft X-ray
  morphology suggests evidence of a loop-loop interaction mechanism:
  the images reveal two parallel magnetic loops prior to the flare,
  and their merging just before onset of the hard X-ray burst. This
  flare therefore provides a chance to examine the two-loop interaction
  model for solar flares. It is found (1) that the observed soft X-ray
  behavior of the two loops in the preflare phase well matches to the
  two-loop interaction model between strong and weak current loops and
  (2) that the observed time scale of the two-loop coalescence is almost
  equal to that estimated from explosive-reconnection theory. In the
  impulsive phase, it is found (3) that the loop-top portion near to the
  interaction region first brightens in the 14--23 keV hard X-rays and (4)
  that the 23--33 keV hard X-ray emission around the peak time originates
  dominantly from two compact sources at the two ends of the merging
  loops. These hard X-ray observations are explained by high-energy
  electrons that are produced in the two current loop interaction.

Title: Imaging Spectra of Hard X-Rays from the Footpoints of Solar
    Impulsive Loop Flares
Authors: Takakura, Tatsuo; Kosugi, Takeo; Sakao, Taro; Makishima,
   Kazuo; Inda-Koide, Mika; Masuda, Satoshi
Bibcode: 1995PASJ...47..355T
Altcode:
  The imaging spectra of hard X-rays emitted from one or both footpoints
  of solar impulsive loop flares seem to frequently show a better fit
  to an extremely hot thermal spectrum, on the order of 10(8) K, than to
  a power-law spectrum, in the main phase of the bursts. In the present
  study this tendency has been verified by the spectra of nine impulsive
  bursts having a sufficient flux for reliable imaging in the H-band
  (52.7--92.8 keV) of the hard X-ray telescope (HXT) aboard the Yohkoh
  spacecraft. The spectral indexes at the footpoints were derived from the
  hard X-ray images in four energy bands of the HXT; their reliability was
  verified by mapping simulations. Since the X-ray spectrum depends on the
  location in the X-ray loop, the spectrum of the total flux is generally
  different from the spatially resolved spectra. The imaging spectrum is
  thus crucial for studying the nature of the electrons emitting hard
  X-rays. The heat conduction of an extremely hot quasi-thermal plasma
  seems to play an essential role in impulsive loop flares.

Title: Hard and Soft X-Ray Observations of Solar Limb Flares
Authors: Mariska, J. T.; Sakao, T.; Bentley, R. D.
Bibcode: 1995SPD....26.1312M
Altcode: 1995BAAS...27..989M
  No abstract at ADS

Title: Coordinated X-ray and Hα Observations of Eruptive Flares
Authors: Wülser, J. -P.; Canfield, R. C.; Sakao, T.; Acton, L. W.
Bibcode: 1995SPD....26.1315W
Altcode: 1995BAAS...27..990W
  No abstract at ADS

Title: Evolution of a Flare Source Inferred from Hard X-Ray and
Radio Observations: Solar Burst on 1992 October 27
Authors: Takakura, Tatsuo; Nishio, Masanori; Nakajima, Hiroshi; Enome,
   Shinzo; Shibasaki, Kiyoto; Takano, Toshiaki; Hanaoka, Yoichiro; Kosugi,
   Takeo; Sakao, Taro; Masuda, Satoshi; Makishima, Kazuo; Inda-Koide, Mika
Bibcode: 1994PASJ...46..653T
Altcode:
  An impulsive burst which occurred on 1992 October 27 was observed
  simultaneously with the hard X-ray telescope on board the Yohkoh
  satellite and the Nobeyama Radioheliograph at 17 GHz. The hard X-ray
  images show a double-source structure during the main phase. One
  footpoint, A, shows a nonthermal spectrum, while another, B, shows
  a better fit to the X-rays from extremely hot thermal electrons
  with about 80 million degrees, flowing into the chromosphere. The
  loop top also shows a better fit to a quasi-thermal spectrum of 75
  million degrees at the main peak. On the other hand, the radio images
  are a larger single source covering the X-ray source, and are highly
  polarized in the L-sense. The larger single image is mainly ascribed
  to the beamwidth, and the single polarization may be due to ``limiting
  polarization". Consequently, the radio source at 17 GHz may be cospatial
  with the X-ray source around the loop top. The radio emission at 17 GHz
  and a part of the emission at 9.4 GHz are attributed to the thermal
  gyro emissions from the extremely hot thermal electrons emitting the
  X-rays. The rest of the radio emission at 9.4 GHz and the emission at
  3.75 GHz are ascribed to thermal gyro emission at the outer layers
  with smaller magnetic fields and lower electron temperatures. The
  intense radio emission at 35 GHz at the main peak is ascribed to
  gyro-synchrotron emission from the nonthermal electrons in footpoint A.

Title: Yohkoh observations of the creation of high-temperature plasma
    in the flare of 16 December 1991
Authors: Culhane, J. L.; Phillips, A. T.; Inda-Koide, M.; Kosugi,
   T.; Fludra, A.; Kurokawa, H.; Makishima, K.; Pike, C. D.; Sakao, T.;
   Sakurai, T.; Doschek, G. A.; Bentley, R. D.
Bibcode: 1994SoPh..153..307C
Altcode:
  Yohkoh observations of an impulsive solar flare which occurred on 16
  December, 1991 are presented. This flare was a GOES M2.7 class event
  with a simple morphology indicative of a single flaring loop. X-ray
  images were taken with the Hard X-ray Telescope (HXT) and soft X-ray
  spectra were obtained with the Bragg Crystal Spectrometer (BCS)
  on board the satellite. The spectrometer observations were made at
  high sensivity from the earliest stages of the flare, are continued
  throughout the rise and decay phases, and indicate extremely strong
  blueshifts, which account for the majority of emission in CaXIX during
  the initial phase of the flare. The data are compared with observations
  from other space and ground-based instruments. A balance calculation
  is performed which indicates that the energy contained in non-thermal
  electrons is sufficient to explain the high temperature plasma which
  fills the loop. The cooling of this plasma by thermal conduction
  is independently verified in a manner which indicates that the loop
  filling factor is close to 100%. The production of `superhot' plasma
  in impulsive events is shown to differ in detail from the morphology
  and mechanisms appropriate for more gradual events.

Title: Particle Acceleration in Flares
Authors: Benz, A. O.; Kosugi, T.; Aschwanden, M. J.; Benka, S. G.;
   Chupp, E. L.; Enome, S.; Garcia, H.; Holman, G. D.; Kurt, V. G.;
   Sakao, T.; Stepanov, A. V.; Volwerk, M.
Bibcode: 1994SoPh..153...33B
Altcode:
  Particle acceleration is intrinsic to the primary energy release in
  the impulsive phase of solar flares, and we cannot understand flares
  without understanding acceleration. New observations in soft and hard
  X-rays, γ-rays and coherent radio emissions are presented, suggesting
  flare fragmentation in time and space. X-ray and radio measurements
  exhibit at least five different time scales in flares. In addition,
  some new observations of delayed acceleration signatures are also
  presented. The theory of acceleration by parallel electric fields is
  used to model the spectral shape and evolution of hard X-rays. The
  possibility of the appearance of double layers is further investigated.

Title: Hard and Soft X-ray Observations of a Super-Hot Thermal Flare
    of 6 February, 1992
Authors: Kosugi, T.; Sakao, T.; Masuda, S.; Hara, H.; Shimizu, T.;
   Hudson, H. S.
Bibcode: 1994kofu.symp..127K
Altcode:
  No abstract at ADS

Title: A Comparison of Hard X-ray, Soft X-ray, and Microwave Sources
    in Solar Flares
Authors: Yaji, K.; Kosugi, T.; Sakao, T.; Masuda, S.; Inda-Koide,
   M.; Hanaoka, Y.
Bibcode: 1994kofu.symp..143Y
Altcode:
  Hard X-ray, soft X-ray, and microwave images of about 20 solar flares
  that occurred in NOAA 7270 are compared for investigating where
  electrons are energized and emit hard X-rays. We find the following:
  (i) Usually hard X-ray sources appear inside a soft X-ray flaring
  loop or loops. The hard X-ray emission tends to originate from the two
  ends of the soft X-ray loop in the impulsive phase (double footpoint
  sources), and later the double sources evolve into a single source
  located near the loop top (loop-top gradual source). (ii) In a few
  cases, another impulsive hard X-ray source with comparable intensity
  with the double footpoint sources appears at a site remote from the
  footpoint sources. This source shows only weak brightening in soft
  X-rays but is bright in microwaves.

Title: Hard X-ray Imaging Observations of Footpoint Sources in
    Impulsive Solar Flares
Authors: Sakao, T.; Kosugi, T.; Masuda, S.; Yaji, K.; Inda-Koide,
   M.; Makishima, K.
Bibcode: 1994kofu.symp..169S
Altcode:
  Hard X-ray imaging observations of intense impulsive flares with the
  Yohkoh Hard X-ray Telescope have revealed that the hard X-ray emission
  in an energy range above 30 keV originates most frequently from double
  sources, suggesting that bulk of hard X-rays is emitted from footpoints
  of flaring magnetic loops. Temporal and spectral behaviors of the
  double sources are described and their physical implications discussed.

Title: Evolution of an Active Region and Flare Productivity
Authors: Kundu, M. R.; Shibasaki, K.; Enome, S.; Nitta, N.; Bruner,
   M.; Sakao, T.; Kosugi, T.
Bibcode: 1994kofu.symp..353K
Altcode:
  We have studied the evolution of an active region (AR 7515) in terms
  of flare productivity. This region appears at the east limb on May 23,
  1993 and then continues its onward march across the disk. We follow
  its evolution until June 2. This region produces many small flares. We
  study the topology, both magnetic and structural of the neighboring
  regions as observed at 17 GHz by the Nobeyama Radio Heliograph (NRH)
  and the Yohkoh/SXT to find their effects on the flare-producing AR. We
  investigate the spatial structure of the flaring region from 17 GHz
  and SXT maps during various times of the impulsive and decay phase,
  to understand the difference in the flaring region spatial structure
  during the preflare, impulsive and decay phases. In general, the maps
  made during these phases show several loops. We try to relate these
  flaring loops with the preflare active region structure.

Title: H_alpha and X-ray Signatures of Chromospheric Heating Observed
    in Solar Flares
Authors: Wuelser, J. -P.; Canfield, R. C.; Sakao, T.; Masuda, S.;
   Kosugi, T.; Tsuneta, S.
Bibcode: 1994kofu.symp..195W
Altcode:
  We have studied the spatial and temporal relationship between
  thermal and non-thermal energy transport, and the chromospheric
  response in solar flares. H_alpha imaging spectra from Mees Solar
  Observatory provided the information on the heating and dynamics in the
  chromosphere, soft X-ray images from Yohkoh provided the conditions
  of the thermal plasma in the corona, and hard X-ray data from Yohkoh
  provided the diagnostics of the non-thermal particles. We present
  some preliminary results for several large flares, and discuss their
  implications for the chromospheric flare heating mechanism.

Title: Alignment of Radio, Soft X-ray, Hard X-ray Images of Sources
    in Impulsive and Gradual Phases of the Flare of 1992 August 17-18
Authors: Enome, S.; Nakajima, H.; Shibasaki, K.; Nishio, M.; Takano,
   T.; Hanaoka, Y.; Torii, C.; Shiomi, Y.; Sekiguchi, H.; Bushimata,
   T.; Kawashima, S.; Shinohara, N.; Irimajiri, Y.; Koshiishi, H.; Choi,
   Y. -S.; Sakai, J.; Takahashi, M.; Takakura, T.; Sakao, T.; Kosugi, T.
Bibcode: 1994kofu.symp..141E
Altcode:
  This is a preliminary report concerning an impulsive flare, which
  occurred on 1992 August 17-18, and was observed with the Nobeyama
  Radioheliograph, Yohkoh, and ground-based instruments. Emphasis is put
  on the alignment of radio images as well as soft X-ray and hard X-ray
  maps, which are compared in both impulsive and gradual phases. In the
  impulsive phase, which continued for about 30 s, nonthermal emission
  was most remarkable at 17 GHz, and was also seen in hard X-rays at the
  southern part of the SXT source, which was about 14" width and 80"
  long, extending in the north-east to south-west direction. Thermal
  emission was detected in soft X-rays and possibly in hard X-rays at the
  northern part. During the gradual phase, about 80 s after the onset of
  the impulsive phase, thermal emission dominated and was located at the
  northern part of the source over the entire energy range. Difficulties
  are discussed concerning a possible simple topology of the magnetic
  fields. Note:This is the abstract of the Letter published PASJ 46,
  L27-31(1994)

Title: Characteristics of solar flare hard X-ray sources as revealed
    with the Hard X-ray Telescope aboard the Yohkoh satellite
Authors: Sakao, T.
Bibcode: 1994PhDT.......335S
Altcode:
  No abstract at ADS

Title: Alignment of Radio, Soft X-Ray, Hard X-Ray Images of Sources
    in Impulsive and Gradual Phases of the Flare of 1992 August 17--18
Authors: Enome, Shinzo; Nakajima, Hiroshi; Shibasaki, Kiyoto; Nishio,
   Masanori; Takano, Toshiaki; Hanaoka, Yoichiro; Torii, Chikayoshi;
   Shiomi, Yasuhiko; Sekiguchi, Hideaki; Bushimata, Takeshi; Kawashima,
   Susumu; Shinohara, Noriyuki; Irimajiri, Yoshihisa; Koshiishi, Hideki;
   Choi, Yong-Seok; Sakai, Jun-Ichi; Takahashi, Masaaki; Takakura,
   Tatsuo; Sakao, Taro; Kosugi, Takeo
Bibcode: 1994PASJ...46L..27E
Altcode:
  This is a preliminary report concerning an impulsive flare, which
  occurred on 1992 August 17--18, and was observed with the Nobeyama
  Radioheliograph, Yohkoh, and ground-based instruments. Emphasis is put
  on the alignment of radio images as well as soft X-ray and hard X-ray
  maps, which are compared in both impulsive and gradual phases. In the
  impulsive phase, which continued for about 30 s, nonthermal emission
  was most remarkable at 17 GHz, and was also seen in hard X-rays at the
  southern part of the SXT source, which was about 14'' width and 80''
  long, extending in the north-east to south-west direction. Thermal
  emission was detected in soft X-rays and possibly in hard X-rays at the
  northern part. During the gradual phase, about 80 s after the onset of
  the impulsive phase, thermal emission dominated and was located at the
  northern part of the source over the entire energy range. Difficulties
  are discussed concerning a possible simple topology of the magnetic
  fields.

Title: Multispectral Observations of Chromospheric Evaporation in
    the 1991 November 15 X-Class Solar Flare
Authors: Wuelser, Jean-Pierre; Canfield, Richard C.; Acton, Loren W.;
   Culhane, J. Leonard; Phillips, Andrew; Fludra, Andrzej; Sakao, Taro;
   Masuda, Satoshi; Kosugi, Takeo; Tsuneta, Saku
Bibcode: 1994ApJ...424..459W
Altcode:
  We analyze simultaneous H(alpha) images and spectra (from Mees
  Solar Observatory), and soft and hard X-ray images and spectra (from
  YOHKOH) during the early phase of an X1.5/3B flare. We investigate
  the morphological relationship between chromospheric downflows,
  coronal upflows, and particle precipitation sites, and the energetic
  relationship between conductive heating, nonthermal particle heating,
  and the chromospheric response. We find that the observations
  consistently fit the chromospheric evaporation model. In particular,
  we demonstrate that the observed upflowing coronal and downflowing
  chromospheric plasma components originate in the same locations,
  and we show that our unique set of optical and X-ray observations
  can clearly distinguish between conductively driven and electron beam
  driven evaporation.

Title: Impulsive Behavior in Solar Soft X-Radiation
Authors: Hudson, H. S.; Strong, K. T.; Dennis, B. R.; Zarro, D.;
   Inda, M.; Kosugi, T.; Sakao, T.
Bibcode: 1994ApJ...422L..25H
Altcode:
  The Yohkoh soft X-ray telescope has observed impulsive, thermal,
  soft X-ray emission at the footpoints of magnetic loops during solar
  flares. The soft X-ray (thermal) time profiles at the footpoints closely
  match the hard X-ray (nonthermal) time profiles, directly demonstrating
  the heating of the lower solar atmosphere on short timescales during
  the interval of nonthermal energy release. This phenomenon is the rule,
  rather than the exception, occurring in the majority of flares that
  we have examined with the Yohkoh data. We illustrate the impulsive
  behavior with data from the major flare of 1992 January 26. For this
  flare, the soft X-ray peak times matched the hard X-ray peak times
  within the time resolution of the soft X-ray measurements (about 10 s),
  and the soft and hard X-ray locations match within the resolution of
  the hard X-ray imager. The impulsive soft X-ray emission clearly has
  a thermal spectral signature, but not at the high temperature of a
  'superhot' source. We conclude that the impulsive soft X-ray emission
  comes from material heated by precipitating electrons at loop footpoints
  and evaporating from the deeper atmosphere into the flaring flux tube.

Title: Time Variation of Hard X-Ray Image in the Early Phase of
    Solar Impulsive Bursts
Authors: Takakura, T.; Inda, M.; Makishima, K.; Masuda, S.; Kosugi,
   T.; Sakao, T.; Sakurai, T.; Ogawara, Y.
Bibcode: 1994xspy.conf...71T
Altcode:
  No abstract at ADS

Title: Particle Acceleration in the 15 November, 1991 Solar Flare
    Observed with HXT
Authors: Sakao, T.; Kosugi, T.; Masuda, S.; Yaji, K.; Inda-Koide,
   M.; Makishima, K.
Bibcode: 1994xspy.conf...91S
Altcode:
  No abstract at ADS

Title: HXT observations of non-thermal hard X-ray sources in solar
    flares.
Authors: Sakao, T.; HXT Team
Bibcode: 1994clis.conf..107S
Altcode:
  The author describes the HXT experiment, from its historical background
  of hard X-ray flare observations, through the instrumentation, to
  newly acquired scientific results.

Title: HXT Observations of the 24 October, 1991, M9.8 Flare
Authors: Masuda, S.; Kosugi, T.; Sakao, T.
Bibcode: 1994xspy.conf..123M
Altcode:
  No abstract at ADS

Title: The Flare of 16 December 1991
Authors: Culhane, J. L.; Phillips, A.; Pike, D.; Inda, M.; Kosugi,
   T.; Sakao, T.
Bibcode: 1994xspy.conf...95C
Altcode:
  No abstract at ADS

Title: The Initial Fifteen Months of Flare Observation with the
    YOHKOH Hard X-Ray Telescope (hxt)
Authors: Kosugi, T.; Sakao, T.; Makishima, K.; Murakami, T.; Masuda,
   S.; Inda-Koide, M.; Yaji, K.; Sawa, M.; Ogawara, Y.
Bibcode: 1994xspy.conf....5K
Altcode:
  No abstract at ADS

Title: Hα and X-Ray Signatures of Chromospheric Evaporation Observed
    during the Early Phase of the 15 November 1991 Flare
Authors: Wülser, J. -P.; Canfield, R. C.; Acton, L. W.; Culhane,
   J. L.; Phillips, A.; Fludra, A.; Sakao, T.; Masuda, S.; Kosugi, T.
Bibcode: 1994xspy.conf...75W
Altcode:
  No abstract at ADS

Title: YOHKOH HXT Observations of a Solar Flare on 16 December, 1991
Authors: Inda-Koide, M.; Makishima, K.; Kosugi, T.; Sakao, T.
Bibcode: 1994xspy.conf...99I
Altcode:
  No abstract at ADS

Title: Time Variation of the Hard X-Ray Image during the Early Phase
    of Solar Impulsive Bursts
Authors: Takakura, Tatsuo; Inda, Mika; Makishima, Kazuo; Kosugi, Takeo;
   Sakao, Taro; Masuda, Satoshi; Sakurai, Takashi; Ogawara, Yoshiaki
Bibcode: 1993PASJ...45..737T
Altcode:
  The time variations of hard X-ray images of four impulsive bursts with
  simple source structures were investigated in a comparison with the
  magnetic structure. Two of them are limb bursts. Common variations
  during the early phase are as follows: i) The hard X-ray brightening
  seems to start at the top of a single coronal loop. ii) The X-ray
  source spreads during the increasing phase of the burst in both
  directions along the loop, and both ends become brighter, especially
  at higher energies with generally unequal brightness. The loop top is
  still bright, especially at lower energies, to show three peaks. The
  speed of the expansion of the X-ray source amounts to about 10(4) km
  s(-1) in three cases. iii) At and after the peak of the X-ray flux,
  the source tends to be a single source at the loop top, especially
  at lower energies. iv) The effective temperature for quasi-thermal
  electrons and their number density during the early phase in the
  vicinity of the loop top are (4--6)times 10(7) K and (5--2)times 10(9)
  cm(-3) , respectively, so that the electron mean free path is greater
  than three-times the local temperature scale height. These observations
  are consistent with the idea that anomalous resistivity, which triggers
  impulsive bursts, is caused by electron plasma waves generated in the
  process of heat conduction.

Title: Survey of Loop-Footpoint Brightenings During the Impulsive
    Phase of Flares
Authors: Strong, K.; Dennis, B.; Hudson, H.; Kosugi, T.; Sakao, T.
Bibcode: 1993BAAS...25Q1187S
Altcode:
  No abstract at ADS

Title: Impulsive Soft X-Ray Emission in Solar Flares
Authors: Hudson, H. S.; Strong, K. T.; Dennis, B. R.; Zarro, D.;
   Inda, M.; Kosugi, T.; Sakao, T.
Bibcode: 1993BAAS...25.1177H
Altcode:
  No abstract at ADS

Title: OVRO Microwave and Yohkoh HXT and SXT Observations of a
    Solar Flare
Authors: Gary, D. E.; Hurford, G. J.; Sakao, T.
Bibcode: 1993BAAS...25.1180G
Altcode:
  No abstract at ADS

Title: Yohkoh-SXT Observations from the Spartan and Nixt Max91
    Campaign
Authors: Morrison, M.; Bruner, M.; Freeland, S.; Lemen, J.; Linford,
   G.; Nitta, N.; Slater, G.; Strong, K.; Hara, H.; Kano, R.; Shimizu,
   T.; Tsuneta, S.; Hudson, H.; Ogawara, Y.; Kosugi, T.; Sakao, T.;
   Watanabe, T.; Takeda, A.; Acton, L.
Bibcode: 1993BAAS...25.1213M
Altcode:
  No abstract at ADS

Title: Hard X-Ray Imaging Observations by YOHKOH of the 15 November
    1991 Flare (Invited)
Authors: Sakao, Taro
Bibcode: 1993ASPC...46..258S
Altcode: 1993mvfs.conf..258S; 1993IAUCo.141..258S
  No abstract at ADS

Title: Correlation between X-ray Temporal Variability and Magnetic
    Environment in Solar Flares
Authors: Nitta, N.; Harvey, K.; Hudson, H.; Ichimoto, K.; Metcalf,
   T.; Mickey, D.; Sakai, J. -I.; Sakao, T.; Sakurai, T.; Takahashi, M.
Bibcode: 1992AAS...181.5503N
Altcode: 1992BAAS...24.1211N
  The X-ray time history of a solar flare can reflect basic processes of
  heating and/or acceleration, which in turn may depend on the magnetic
  environment of the site. Some flares show a simple rise and fall
  temporal behavior, whereas others show more than one peak. Comparisons
  of images taken by the Soft X-ray Telescope (SXT) aboard the Yohkoh
  spacecraft with ground-based magnetic data (Hawaii, Kitt Peak and
  Mitaka) reveal that, at least for a flare-productive active region
  (NOAA 7260), flares with double-peaked and single-peaked time profiles
  occurred at systematically different locations within the region. We
  discuss this result in terms of theoretical models, especially those
  of coalescence of two current loops.

Title: The Hard X-Ray Telescope (HXT) Onboard Yohkoh: Its Performance
    and Some Initial Results
Authors: Kosugi, Takeo; Sakao, Taro; Masuda, Satoshi; Makishima,
   Kazuo; Inda, Mika; Murakami, Toshio; Ogawara, Yoshiaki; Yaji, Kentaro;
   Matsushita, Kyoko
Bibcode: 1992PASJ...44L..45K
Altcode:
  More than two hundred solar flares, including several GOES X-class
  events, were successfully observed with the Hard X-ray Telescope (HXT)
  on board Yohkoh during the initial six months of observations since 1991
  October. Hard X-ray images taken simultaneously in four X-ray energy
  bands (14--23--33--53--93 keV), with angular and temporal resolutions
  of ~ 5 '' and 0.5 s, respectively, have been revealing how and where
  hard X-rays are emitted in flaring magnetic loops, and further how and
  where electrons are accelerated and confined. These HXT observations
  are briefly reviewed from the viewpoint of the instrument capability
  and performance, with some new scientific results.

Title: The X Flare of 1991 November 15: Coordinated Mees/Yohkoh
    Observations
Authors: Canfield, Richard C.; Hudson, Hugh S.; Leka, K. D.; Mickey,
   Donald L.; Metcalf, Thomas R.; Wuelser, Jean-Pierre; Acton, Loren W.;
   Strong, Keith T.; Kosugi, Takeo; Sakao, Taro; Tsuneta, Saku; Culhane,
   J. Leonard; Phillips, Andrew; Fludra, Andrzej
Bibcode: 1992PASJ...44L.111C
Altcode:
  This is a preliminary report on two unique new results from coordinated
  observations at Mees Solar Observatory and Yohkoh of the X1.5 flare
  of 1991 November 15, using vector magnetograms, Hα imaging spectra,
  X-ray images, and X-ray spectra. First, we find a close spatial
  relationship between Hα redshifts and X-rays from a flare loop and
  its footpoints at a time of large X-ray blueshifts. Second, we find
  that impulsive-phase hard X-rays originate in regions that are near,
  but not coincident with, the peaks of the vertical electrical current
  density distribution in AR 6919.

Title: Hard X-Ray Imaging Observations by YOHKOH of the 1991 November
    15 Solar Flare
Authors: Sakao, Taro; Kosugi, Takeo; Masuda, Satoshi; Inda, Mika;
   Makishima, Kazuo; Canfield, Richard C.; Hudson, Hugh S.; Metcalf,
   Thomas R.; Wuelser, Jean-P.; Acton, Loren W.; Ogawara, Yoshiaki
Bibcode: 1992PASJ...44L..83S
Altcode:
  We report on hard X-ray imaging observations of the 1991 November 15
  flare with the HXT instrument aboard {Yohkoh}. Distributions of the hard
  X-ray sources at various stages of the flare, together with an overlay
  of the white-light flare, are presented. Attention is concentrated on
  the behavior of hard X-ray sources during the impulsive phase. The
  hard X-ray source appeared initially as a single source near the
  magnetic neutral line, then evolved into a double-source shape with the
  separation increasing with time. We believe that this is evidence for a
  multiple loop system flaring successively with a rising energy-release
  site. At the minima between the individual spikes of the time profile,
  the hard X-rays at 20--30 keV were concentrated near the apex of the
  flaring loop, whereas the hard X-rays above 30 keV originated from the
  footpoints. These observations are compared with the existing models.

Title: November 15, 1991 X Flare -- The Movie: Hα , Soft X-rays,
    and Hard X-rays and Magnetic Fields
Authors: Wulser, J. -P.; Acton, L.; Sakao, T.; Canfield, R.; Kosugi,
   T.; Slater, G.; Strong, K.; Tsuneta, S.
Bibcode: 1992AAS...180.3003W
Altcode: 1992BAAS...24..775W
  The X1.5/3B flare on 1991 November 15, 22:33 UT was well observed
  by the Hα Imaging Spectrograph and the Vector Magnetograph
  (Stokes Polarimeter) at Mees Solar Observatory, and by the Soft-
  and Hard X-ray Telescopes (SXT and HXT) aboard YOHKOH. We have
  combined this multispectral dataset into a series of temporally and
  spatially co-aligned video movies and analyzed the morphological
  and temporal relationships of the various flare emissions. The
  earliest manifestations of this flare include unresolved preflare SXR
  brightenings very close to the magnetic neutral line and preflare
  motions of filaments seen in Hα . In the flare core, SXR and Hα
  emission show moving and rotating coronal structures which we interpret
  as a successive brightening of adjacent loops during the main phase
  of the flare. The HXR source shows much more dramatic variability
  than the SXR source, and they are clearly not cospatial. On the other
  hand, there is a close spatial relationship between the HXR and Hα
  blue wing emission sites. The Hα , HXR, and SXR images all point to
  acceleration and heating in a region that starts close to the neutral
  line and moves outward during each HXR burst and during the gradual
  phase. Spectacular mass ejections are seen in both SXR and Hα , with
  clear unwinding of tightly coiled structures, acceleration of X-ray
  and Hα material to velocities of order 1000 km/s, and a striking
  thermal bifurcation between hot and cold plasma.

Title: Preliminary Results from HXT Aboard YOHKOH
Authors: Kosugi, T.; Sakao, T.; Masuda, S.; Makishima, K.; Inda, M.;
   Yaji, K.; Matsushita, K.; Ogawara, Y.
Bibcode: 1992AAS...180.2302K
Altcode: 1992BAAS...24..759K
  Several hundred solar flares, including several X-class flares, have
  been observed successfully with the Hard X-ray Telescope (HXT) aboard
  YOHKOH during the initial six-month observation period. The hard X-ray
  images taken simultaneously in four energy bands covering from 15 to
  100 keV with angular and temporal resolution of about 5 arcsec and 0.5
  s, respectively, reveal the acceleration and confinement mechanisms of
  energetic electrons in solar flares, with the aid of soft X-ray images
  also taken by YOHKOH and ground-based observations. This paper provides
  the following: (i), a summary of the instrumental performance of HXT
  from the point of view of its science capability, i.e., sensitivity,
  imaging quality, etc.; (ii), a statistical derivation of the average
  height of hard X-ray sources (dependent on the observing photon
  energies) and a comparison with existing theories; (iii), case studies
  of source characteristics of several well-observed flares.

Title: Soft X-ray Blueshifts and Hα Redshifts in the November 15,
    1991 X-Class Flare
Authors: Wulser, J. -P.; Acton, L.; Canfield, R.; Culhane, L.; Fludra,
   A.; Masuda, S.; Phillips, A.; Sakao, T.
Bibcode: 1992AAS...180.1805W
Altcode: 1992BAAS...24..755W
  We analyzed simultaneous Hα line profile observations (from Mees Solar
  Observatory), CaXIX line profile observations (from the Bragg Crystal
  Spectrometer aboard YOHKOH), and soft- and hard X-ray images (from SXT
  and HXT on YOHKOH) of the November 15, 1991 X-class flare. The observed
  CaXIX emission shows strong blueshifts very early in the flare. The soft
  X-ray images suggest that this blueshifted emission originates from
  one or more of three localized soft X-ray bright points. At the same
  time, the Hα line profile shows redshifted and blueshifted emission
  in several locations. Two Hα redshift kernels are associated with the
  two brightest soft X-ray sources. On the basis of their relationship
  to the magnetic neutral line and their subsequent development, we
  conclude that these Hα redshift kernels are the footpoints of a
  single loop, which initially exhibits two soft X-ray bright points
  in the loop legs. The results suggest that chromospheric evaporation
  is the responsible mechanism for the observed Hα redshifts and CaXIX
  blueshifts in the early stage of the flare. The independent hard X-ray
  (HXT) and Hα observations both indicate that this chromospheric
  evaporation is not associated with strong non-thermal electron
  precipitation. The third soft X-ray bright point, the faintest of the
  three, is not associated with redshifted Hα emission. This bright spot
  develops into a connection between the second Hα redshift kernel,
  and another Hα kernel with strong blueshifts. The Hα blueshift is
  associated with a mass ejection phenomenon.

Title: Electric Currents and Hard X-ray Images in the X Class Flare
    of November 15, 1991
Authors: Metcalf, T. R.; Sakao, T.; Acton, L. W.; Canfield, R. C.;
   Hudson, H. S.; Inda, M.; Kosugi, T.; Wulser, J. P.
Bibcode: 1992AAS...180.3005M
Altcode: 1992BAAS...24..776M
  We present co-aligned observations of hard x-rays observed with the
  Hard X-ray Telescope (HXT) on board the YOHKOH spacecraft and vertical
  electric currents derived from a vector magnetogram obtained at the
  Mees Solar Observatory, Haleakala, Hawaii. Previous work comparing
  the wings of the Hα line to vertical electric currents has suggested
  that electron precipitation in flares occurs at the edges of these
  currents. The Stark wings of Hα were interpreted as a signature of
  non-thermal electrons penetrating the relatively dense chromosphere and
  used as a proxy for direct observation of the non-thermal electrons. The
  hard X-rays used in this study provide a direct determination of
  the locations of the electron energy losses. In the X class flare
  of November 15, 1991, we find the same relation between hard X-ray
  emission and vertical electric currents as was found between Hα Stark
  wing emission and vertical currents: the hard x-ray emission occurs
  predominantly at the edges of the vertical current sites, and not
  spatially on top of these currents. Canfield, R. C., de La Beaujardiere,
  J., and Leka, K. D., in ``The Physics of Solar Flares", ed. Culhane and
  Jordan, The Royal Society, London, 1991 Canfield, R. C., Leka, K. D.,
  and Wulser,J. P., in ``Flare Physics in Solar Activity Maximum 22",
  ed. Uchida, Canfield, Watanabe, and Hiei, Springer-Verlag, Berlin, 1991

Title: Hard X-rays from the contact binary VW Cephei.
Authors: Tsuru, T.; Makishima, K.; Ohashi, T.; Sakao, T.; Pye, J. P.;
   Williams, O. R.; Barstow, M. A.; Takano, S.
Bibcode: 1992MNRAS.255..192T
Altcode:
  Ginga observations of the contact binary VW Cep are presented. The
  observed X-ray luminosity is 1.1 x 10 exp 30 erg/s in the energy range
  of 2-10 keV, assuming a distance of 31 pc. No evidence for X-ray
  orbital modulation or for flare events was detected. The observed
  X-ray spectrum is very hard, and can be represented well either by a
  thermal bremsstrahlung model with a temperature of 11.2 +40/-2.3 keV
  or a power-law model with a photon index of 1.90 +0.24/-0.20. These
  observational results are interpreted in terms of the thermal emission
  from a hot coronal plasma extending beyond the stellar size. The
  observed upper limit on the iron K-line intensity is considerably
  lower than the theoretical prediction.

Title: GINGA observations of the old nova GK Persei in quiescence
    and outburst.
Authors: Ishida, M.; Sakao, T.; Makishima, K.; Ohashi, T.; Watson,
   M. G.; Norton, A. J.; Kawada, M.; Koyama, K.
Bibcode: 1992MNRAS.254..647I
Altcode:
  Ginga observations of the old nova GK Persei in quiescence, as well
  as a brief scanning observation during an outburst are reported. The
  X-ray spectrum in quiescence is well fitted by thermal bremsstrahlung
  emission of very high temperature (approximately 30 keV), plus an
  iron emission line. The outburst spectrum is complex and comprises two
  continua with different column densities (about 10 exp 23 and about 10
  exp 24/sq cm). The 351-s spin modulation of GH Per was clearly detected
  in the quiescence observation, which confirms the results of previous
  Exosat observations. The folded light curve shows two peaks that are
  not separated by 180 deg in phase, which is quite different from the
  Exosat outburst data. It is similar to the Exosat observation at a
  similar flux level.

Title: The Hard X-ray Telescope (HXT) for the SOLAR-A mission
Authors: Kosugi, T.; Makishima, K.; Murakami, T.; Sakao, T.; Dotani,
   T.; Inda, M.; Kai, K.; Masuda, S.; Nakajima, H.; Ogawara, Y.; Sawa,
   M.; Shibasaki, K.
Bibcode: 1991SoPh..136...17K
Altcode:
  The Hard X-ray Telescope (HXT) is a Fourier-synthesis imager; a set of
  spatially-modulated photon count data are taken from 64 independent
  subcollimators and are Fourier-transformed into an image by using
  procedures such as the maximum entropy method (MEM) or CLEAN. The
  HXT takes images of solar flares simultaneously in four energy bands,
  nominally 15 (or 19)-24, 24-35, 35-57, and 57-100 keV, with an ultimate
  angular resolution as fine as ∼ 5 arc sec and a time resolution 0.5
  s. Each subcollimator has a field of view wider than the solar disk. The
  total effective area of the collimator/detector system reaches ∼ 70
  cm<SUP>2</SUP>, about one order of magnitude larger than that of the
  HINOTORI hard X-ray imager. Thanks to these improvements, HXT will for
  the first time enable us to take images of flares at photon energies
  above ∼ 30 keV. These higher-energy images will be compared with
  lower-energy ones, giving clues to the understanding of nonthermal
  processes in solar flares, i.e., the acceleration and confinement of
  energetic electrons. It is of particular importance to specify the
  acceleration site with regard to the magnetic field figuration in a
  flaring region, which will be achieved by collaborative observations
  between HXT and the Soft X-ray Telescope on board the same mission.

Title: Non-periodic intensity variations in the X-ray pulsar GX301-2.
Authors: Tashiro, M.; Makishima, K.; Ohashi, T.; Sakao, T.; Sansom,
   A. E.
Bibcode: 1991MNRAS.252..156T
Altcode:
  Results of Ginga observations of the X-ray binary pulsar GX301 -
  1 are analyzed for their temporal and spectral properties in order
  to determine whether 'self-similar variation' (SSV) is a common
  phenomenon among X-ray pulsars. The unambiguous detection of aperiodic
  intensity variations of 7-10 percent rms relative amplitude over
  time-scales covering about 16 to 0.1 s is reported. These variations
  are self-similar, being well fitted by a power law in power spectral
  density versus frequency space. The pulse period measured is 689.80
  s, the shortest measured for this source to date. The fraction of
  X-rays which is pulsed is energy dependent, being greater at higher
  energies. The fractional aperiodic variability shows no such energy
  dependence, nor do they appear to be significantly dependent on the
  source intensity, pulse phase, or absorbing column measured. It is
  inferred that the aperiodic variations are not caused by absorption
  variations, but are intrinsic to the source.

Title: Cyclotron Line Features in the Spectrum of the Transient
    X-Ray Pulsar X0115+634
Authors: Nagase, F.; Dotani, T.; Tanaka, Y.; Makishima, K.; Mihara,
   T.; Sakao, T.; Tsunemi, H.; Kitamoto, S.; Tamura, K.; Yoshida, A.;
   Nakamura, H.
Bibcode: 1991ApJ...375L..49N
Altcode:
  An outburst of the transient X-ray pulsar X0115 + 634 was detected with
  the All Sky Monitor (ASM) on board Ginga on February 5, 1990. Follow-up
  observations with the large-area proportional counters (LACs) revealed
  complex changes in the energy spectrum which depend on the phase of
  the 3.6 s pulsation. Characteristic structures in the spectra above 10
  keV can be best interpreted as two dips at about 12 and about 23 keV,
  although not at all phases. The results strongly suggest that the
  structures in the spectra are due to cyclotron resonant scattering
  and the two apparent absorption lines are ascribed to the fundamental
  and second harmonics. This indicates a magnetic field strength on the
  neutron star surface of about 1 x 10 to the 12th G. Equivalent widths
  of the second harmonic line are about 2 times larger than those of
  the first harmonic line, depending on the pulse phase.

Title: Multi-Frequency Observations of H2106-099: A Weak Blue Bump,
    Variable Seyfert 1 with Strong UV Fe II
Authors: Grossan, B.; Remillard, R.; Bradt, H.; Brissenden, R.; Sakao,
   T.; Ohashi, T.
Bibcode: 1991BAAS...23..921G
Altcode:
  No abstract at ADS

Title: The SOLAR-A Hard X-ray Telescope (HXT)
Authors: Kosugi, T.; Makishima, K.; Inda, M.; Murakami, T.; Dotani,
   T.; Inda, M.; Kai, K.; Masuda, S.; Nakajima, H.; Ogawara, Y.; Sakao,
   T.; Sawa, M.; Shibasaki, K.
Bibcode: 1991AdSpR..11e..81K
Altcode: 1991AdSpR..11...81K
  The Hard X-ray Telescope (HXT), now under fabrication for the SOLAR-A
  mission (scheduled for launch in August 1991), is an advanced
  Fourier-synthesis imager. An overview of the HXT instrument is
  given together with its scientific objectives, that is, the electron
  acceleration and confinement mechanisms in solar flares. Scientific
  return from HXT will be greatly increased if worldwide collaboration
  with other space and ground-based observations is well organized.

Title: The Hard X-ray Telescope (HXT) on Board SOLAR-A (Extended
    Abstract)
Authors: Sakao, Taro; HXT Group
Bibcode: 1991LNP...387...20S
Altcode: 1991fpsa.conf...20S
  No abstract at ADS

Title: Discovery of a Prominent Cyclotron Absorption Feature from
    the Transient X-Ray Pulsar X0331+53
Authors: Makishima, K.; Mihara, T.; Ishida, M.; Ohashi, T.; Sakao,
   T.; Tashiro, M.; Tsuru, T.; Kii, T.; Makino, F.; Murakami, T.; Nagase,
   F.; Tanaka, Y.; Kunieda, H.; Tawara, Y.; Kitamoto, S.; Miyamoto, S.;
   Yoshida, A.; Turner, M. J. L.
Bibcode: 1990ApJ...365L..59M
Altcode:
  A remarkable absorption feature at 28.5 keV, attributable to electron
  cyclotron resonance, has been discovered in the 1.9-60-keV X-ray
  spectrum of the recurrent transient X-ray pulsar X0331 + 53. The
  observed resonance energy implies a neutron star surface magnetic
  field of 2.5(1 + z) x 10 to the 12th G, where z is the gravitational
  redshift. The detection was made with the Ginga observatory in October
  1989, during an outburst of this transient with a flux level of about
  0.3 Crab. The feature is very deep and has been resolved with excellent
  statistics. This is the fourth unambiguous detection of cyclotron
  resonant scattering features from X-ray pulsars, suggesting that these
  features are a common phenomenon among these objects. An empirical
  relation found between the cyclotron resonance energy and the spectral
  cutoff energy suggests that the magnetic field strengths of the known
  X-ray pulsars are clustered in a range (1-4) x 10 to the 12th G.

Title: When will the peculiar X-ray pulsar GX 1+4 resume the fast
    spin-up?
Authors: Sakao, T.; Makishima, K.; Ohashi, T.; Dotani, T.; Kani, T.;
   Makino, T. K. F.; Nagase, F.; Takeshima, T.
Bibcode: 1990MNRAS.246P..11S
Altcode:
  Results from observations of the ∼110-s X-ray pulsar GX 1+4
  (4U 1728-24), made with the GINGA satellite in 1989 August, are
  reported. The absorption- corrected 2-20-keV luminosity of the source
  was 1.2 × 10<SUP>37</SUP> erg s<SUP>-1</SUP> at an assumed distance
  of 10 kpc, which is ∼10 and ∼2 times larger than in 1987 March
  and 1988 March, respectively. This implies that GX 1+4 is emerging
  from the extended low state which lasted over the middle 1 980s. The
  observed pulse period, P = 113.626±0.002 s, indicates that GX 1+4
  has been spinning down monotonically at least since 1987 March, in
  contrast to the fast spin-up observed through the 1970s. A remarkable
  discovery is that the intensity increase since 1987 has hardly
  affected the spin-down rate, P<SUP>ṡ</SUP>=4.5 × 10<SUP>-8</SUP>
  s s<SUP>-1</SUP>. The 2-30-keV source spectrum is little different in
  shape from those observed in the 1970s.

Title: New observations of the cyclotron absorption feature in
    Hercules X-1
Authors: Mihara, T.; Makishima, K.; Ohashi, T.; Sakao, T.; Tashiro, M.
Bibcode: 1990Natur.346..250M
Altcode:
  ALTHOUGH neutron stars are generally believed to be born with intense
  (10<SUP>11</SUP>-10<SUP>13</SUP> G) magnetic fields<SUP>1,2</SUP>,
  which then gradually decay<SUP>3</SUP>, measurements of their field
  strengths remain uncertain. In the special case of X-ray-emitting
  binary pulsars, a direct estimate of the field strength can be
  obtained by measuring the energy of spectral features that are due to
  electron cyclotron resonance<SUP>4-13</SUP>. With the Ginga satellite
  observatory<SUP>14,15</SUP>, we have measured a cyclotron feature in
  the hard X-ray spectrum of the 1.24-s binary pulsar Hercules X-1 with
  a much greater energy resolution than in previous observations4-9. The
  spectrum from 10-60 keV can be described with a simple analytical
  formula<SUP>12,16,17</SUP>, which indicates an absorption feature at ~34
  keV rather than an emission feature at ~50keV. From this we estimate
  the surface magnetic field strength of Her X-1 to be (2.9+/-0.3)
  × 10<SUP>12</SUP> G.

Title: Discovery of a Cyclotron Absorption Line in the Spectrum of
    the Binary X-Ray Pulsar 4U 1538-52 Observed by GINGA
Authors: Clark, George W.; Woo, Jonathan W.; Nagase, Fumiaki;
   Makishima, Kazuo; Sakao, Taro
Bibcode: 1990ApJ...353..274C
Altcode:
  A cyclotron absorption line near 20 keV has been found in the
  spectrum of the massive eclipsing binary X-ray pulsar 4U 1538 - 52 in
  observations with the Ginga observatory. The line is detected throughout
  the 529 s pulse cycle with a variable equivalent width that has its
  maximum value during the smaller peak of the two-peak pulse profile. It
  is found that the profile of the pulse and the phase-dependence of the
  cyclotron line can be explained qualitatively by a pulsar model based on
  recent theoretical results on the properties of pencil beams emitted by
  accretion-heated slabs of magnetized plasma at the magnetic poles of a
  neutron star. The indicated field at the surface of the neutron star is
  1.7 (1 + z) x 10 to the 12th G, where z is the gravitational redshift.

Title: Peculiar pulse profile of GX 1+4 observed in the spin-down
    phase.
Authors: Dotani, T.; Kii, T.; Nagase, F.; Makishima, K.; Ohashi, T.;
   Sakao, T.; Koyama, K.; Tuohy, I. R.
Bibcode: 1989PASJ...41..427D
Altcode:
  Observations of GX 1+4 made with Ginga in March 1987 and March 1988 have
  revealed the following drastic changes in the system: (1) spin-down at
  an average rate of 1.2 x 10 to the-2nd/yr, (2) an extended low state
  with a luminosity of 1.2 x 10 to the 36th erg/s in 1987 and 5.7 x 10
  to the 36th erg/s in 1988, and (3) a peculiar pulse profile witha sharp
  dip associated with a narrow maximum. One possible interpretation of the
  rapid spin-down rate requires a magnetic dipole moment of 5 x 10 to the
  31st G cu cm. However, this interpretation seems implausible. Instead,
  a retrograde rotating accretion disk is proposed to explain the present
  spin-down of GX 1+4 and its rate of change. The dip structure with a
  narrow maximum seems to result from resonance scattering of photons
  at the accretion column above the magnetic pole.

Title: Spin-down of the X-ray pulsar GX1 +4 during an extended
    low state
Authors: Makishima, K.; Ohashi, T.; Sakao, T.; Dotani, T.; Inoue,
   H.; Koyama, K.; Makino, F.; Mitsuda, K.; Nagase, F.; Thomas, H. D.;
   Turner, M. J. L.; Kii, T.; Tawara, Y.
Bibcode: 1988Natur.333..746M
Altcode:
  X-ray pulsars<SUP>1,2</SUP> are magnetized, spinning neutron stars
  accreting matter from their binary companions. Their pulse periods
  P, ranging over four orders of magnitude, increase and decrease in
  complex ways<SUP>1,3,4</SUP>. The more luminous ones tend to show faster
  spin-up<SUP>1,5</SUP>. A puzzle is that the spin-up timescales of many
  X-ray pulsars are much shorter than their binary-evolution timescales,
  thus apparently violating the steady-state condition. It has there-fore
  been suspected<SUP>6</SUP> that there exist many 'turned-off X-ray
  pulsars currently spinning down undetected. An excellent test for this
  hypothesis became available using the X-ray pulsar GX1 +4, which used
  to show the fastest spin-up over a decade<SUP>1,7-10 </SUP>and then
  faded away<SUP>11</SUP>. Using the X-ray satellite Ginga<SUP>12</SUP>,
  we detected GX1+4 at ~1/40 the previous intensity, and found that it
  now has an average spin-down trend. This discovery apparently supports
  the above hypothesis.