Author name code: kano
ADS astronomy entries on 2022-09-14
author:"Kano, Ryouhei"
------------------------------------------------------------------------
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: CASPER: A mission to study the time-dependent evolution of
the magnetic solar chromosphere and transition regions
Authors: Orozco Suárez, D.; del Toro Iniesta, J. C.; Bailén, F. J.;
López Jiménez, A.; Balaguez Jiménez, M.; Bellot Rubio, L. R.;
Ishikawa, R.; Katsukawa, Y.; Kano, R.; Shimizu, T.; Trujillo Bueno,
J.; Asensio Ramos, A.; del Pino Alemán, T.
Bibcode: 2022ExA...tmp...26O
Altcode:
Our knowledge about the solar chromosphere and transition region (TR)
has increased in the last decade thanks to the huge scientific return
of space-borne observatories like SDO, IRIS, and Hinode, and suborbital
rocket experiments like CLASP1, CLASP2, and Hi-C. However, the magnetic
nature of those solar regions remain barely explored. The chromosphere
and TR of the Sun harbor weak fields and are in a low ionization stage
both having critical effects on their thermodynamic behavior. Relatively
cold gas structures, such as spicules and prominences, are located in
these two regions and display a dynamic evolution in high-resolution
observations that static and instantaneous 3D-magnetohydrodynamic (MHD)
models are not able to reproduce. The role of the chromosphere and TR
as the necessary path to a (largely unexplained) very hot corona calls
for the generation of observationally based, time-dependent models
of these two layers that include essential, up to now disregarded,
ingredients in the modeling such as the vector magnetic field. We
believe that the community is convinced that the origin of both the
heat and kinetic energy observed in the upper layers of the solar
atmosphere is of magnetic origin, but reliable magnetic field
measurements are missing. The access to sensitive polarimetric
measurements in the ultraviolet wavelengths has been elusive until
recently due to limitations in the available technology. We propose a
low-risk and high-Technology Readiness Level (TRL) mission to explore
the magnetism and dynamics of the solar chromosphere and TR. The mission
baseline is a low-Earth, Sun-synchronous orbit at an altitude between
600 and 800 km. The proposed scientific payload consists of a 30 cm
aperture telescope with a spectropolarimeter covering the hydrogen
Ly-alpha and the Mg II h&k ultraviolet lines. The instrument shall
record high-cadence, full spectropolarimetric observations of the
solar upper atmosphere. Besides the answers to a fundamental solar
problem the mission has a broader scientific return. For example,
the time-dependent modeling of the chromospheres of stars harboring
exoplanets is fundamental for estimating the planetary radiation
environment. The mission is based on technologies that are mature
enough for space and will provide scientific measurements that are
not available by other means.
Title: Empirical relations between the intensities of Lyman lines
of H and He+
Authors: Gordino, M.; Auchère, F.; Vial, J. -C.; Bocchialini, K.;
Hassler, D. M.; Bando, T.; Ishikawa, R.; Kano, R.; Kobayashi, K.;
Narukage, N.; Trujillo Bueno, J.; Winebarger, A.
Bibcode: 2022A&A...657A..86G
Altcode: 2022arXiv220101519G
Context. Empirical relations between major UV and extreme UV spectral
lines are one of the inputs for models of chromospheric and coronal
spectral radiances and irradiances. They are also needed for the
interpretation of some of the observations of the Solar Orbiter
mission.
Aims: We aim to determine an empirical relation between
the intensities of the H I 121.6 nm and He II 30.4 nm Ly-α lines.
Methods: Images at 121.6 nm from the Chromospheric Lyman-Alpha
Spectro Polarimeter (CLASP) and Multiple XUV Imager (MXUVI) sounding
rockets were co-registered with simultaneous images at 30.4 nm from the
EIT and AIA orbital telescopes in order to derive a spatially resolved
relationship between the intensities.
Results: We have obtained
a relationship between the H I 121.6 nm and He II 30.4 nm intensities
that is valid for a wide range of solar features, intensities, and
activity levels. Additional SUMER data have allowed the derivation of
another relation between the H I 102.5 nm (Ly-β) and He II 30.4 nm
lines for quiet-Sun regions. We combined these two relationships to
obtain a Ly-α/Ly-β intensity ratio that is comparable to the few
previously published results.
Conclusions: The relationship
between the H I 121.6 nm and He II 30.4 nm lines is consistent with the
one previously obtained using irradiance data. We have also observed
that this relation is stable in time but that its accuracy depends on
the spatial resolution of the observations. The derived Ly-α/Ly-β
intensity ratio is also compatible with previous results.
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: Determination of Large Scale Plasma Properties of Solar Corona
Using the X-Ray Telescope onboard Hinode: IV. Detailed Calibration
of the Off-Axis Data
Authors: Shin, J.; Kano, R.; Sakurai, T.; Kim, Y.; Moon, Y.
Bibcode: 2021AAS...23831307S
Altcode:
Coronal hole is important not only in the field of solar physics but
also of space weather because it is known as the origin of the fast
solar wind. However, the detailed mechanism of coronal heating leading
to the acceleration of solar wind is still unknown to us. Theoretical
modeling of the three-dimensional coronal structures is sensitive
to the values of plasma properties at the base of solar corona and
thus requires in advance accurate empirical description of those
properties. Therefore, the study on the physical conditions of solar
plasma in the coronal holes and near the off-limb areas will give us an
essential clue to understand the boundary conditions on the mechanism
of heating the coronal plasma. The X-Ray Telescope (XRT) onboard Hinode
equips the modified grazing incidence (GI) mirror whose FOV is 34 x
34 arcmin covering the full solar disk and its neighboring regions,
and as a result, the targets near the limb area are usually placed
far from the center. For this reason, the imaging artefacts shown in
the off-axis region should be calibrated carefully in order for the
observed data to be properly interpreted. We will introduce in
this presentation the methods of how to calibrate the data taken near
the periphery of Hinode/XRT full FOV, which include the restoration
of the scattered light and the reduction of vignetting effect. We
have analyzed over-exposed in-flight images during the solar flare
to estimate the amount of scattered light inherent in the observed
data. It is revealed the light scattered due to the roughness of GI
mirror surface has a power-law distribution and its amount depends on
the energy considered, which allows us to complete a PSF profile from
the core to the scattering wing. We have also evaluated the vignetting
effect in Hinode/XRT by analyzing the 2D distribution of effective area
in the FOV taken from pre-launch experiments. Many interesting results
on the optical characteristics will be introduced in our presentation.
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 &
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: Detailed Calibration of the Off-Axis Optical Characteristics
for the X-Ray Telescope onboard Hinode
Authors: Shin, Junho; Kano, Ryouhei; Sakurai, Takashi; Kim, Yeon-Han;
Moon, Yong-Jae
Bibcode: 2021EGUGA..2313004S
Altcode:
The X-Ray Telescope (XRT) onboard the Hinode satellite has a
specially designed Wolter type grazing-incidence (GI) optics with a
paraboloid-hyperboloid mirror assembly to measure the solar coronal
plasma of temperatures up to 10 MK with a resolution of about one
arc sec. One of the main purposes of this scientific mission is to
investigate the detailed mechanism of energy transfer processes from
the photosphere to the upper coronal region leading to its heating and
the solar wind acceleration. An astronomical telescope is in general
designed such that the best-focused image of an object is achieved at or
very close to the optical axis, and inevitably the optical performance
deteriorates away from the on-axis position. The Sun is, however, a
large astronomical object and thus targets near the limb of full-disk
images are placed at the outskirt of the field of view. The design of a
solar telescope should thus consider the uniformity of imaging quality
over a wide FOV, and it is particularly so for X-ray telescopes whose
targets can be in the corona high above the limb. We will explain in
this presentation the importance of detailed calibration of the off-axis
optical characteristics for Hinode/XRT. It have been revealed that
the scattered light caused by the GI mirror surface has a power-law
distribution and shows an energy dependence. We will also introduce
the basic scheme of how the level of scattering wing is determined and
connected to the core from the analysis of highly saturated in-flight
data. Vignetting is another important optical characteristics for
describing the telescope's performance, which reflects the ability to
collect incoming light at different locations and photon energies. We
have evaluated the vignetting effect in Hinode/XRT by analyzing
the ground experimental data and found that the degree of vignetting
varies linearly from the optical center and its pattern shows an energy
dependence. Many interesting results on the calibration of Hinode/XRT
optical characteristics will be introduced and discussed thoroughly.
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 $h$ & $k$ 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: Determination of Large Scale Plasma Properties of Solar
Corona Using the X-Ray Telescope onboard Hinode: III. PSF and Image
Calibration
Authors: Shin, Junho; Sakurai, Takashi; Kano, Ryouhei; Kim, Yeon-Han;
Moon, Yong-Jae
Bibcode: 2021cosp...43E1049S
Altcode:
To theoretically model the three dimensional coronal structures is
sensitive to the values of plasma properties at the base of solar
corona and thus requires beforehand accurate empirical description of
those properties. Detailed studies on the physical state of coronal
plasma near the off-limb areas will therefore lead us to understand
the mechanism of energy transfer processes from the photosphere to
the upper coronal region leading to its heating and the solar wind
acceleration. The Hinode X-Ray Telescope (XRT) has contributed to
the progress in our understanding of coronal physics for more than a
decade. Since the telescope was designed to observe the Sun in the wide
field of view covering full solar disk, targets near the limb area are
placed at the outskirt of FOV. The optical performance of the instrument
gradually deteriorates as it goes away from the optical center and thus
the off-axis characteristics of Hinode/XRT should be examined with care
in order to precisely interpret the coronal plasma properties near
the solar limb area. This presentation will explain the importance
of accurate calibration of the optical characteristics, especially
for the data taken in the off-axis region. Our previous research has
shown that the light scattered by the XRT mirror surface roughness has
a power-law distribution and also shows an energy dependence, with
which the PSF profile from the core to the scattering wing has been
completed. We will introduce in this study how the level of scattering
wing can be determined quantitatively for each focal plane filter
from in-flight data analysis. We have also evaluated the vignetting
effect in Hinode/XRT by analyzing the distribution of effective area
taken from MSFC/XRCF pre-launch experiment. More interesting results
on the calibration of Hinode/XRT scattered light and the correction
of vignetting effect will be introduced and discussed thoroughly.
Title: Optical design of the Chromospheric LAyer Spectro-Polarimeter
(CLASP2)
Authors: Tsuzuki, Toshihiro; Ishikawa, Ryohko; Kano, Ryouhei; Narukage,
Noriyuki; Song, Donguk; Yoshida, Masaki; Uraguchi, Fumihiro; Okamoto,
Takenori J.; McKenzie, David; Kobayashi, Ken; Rachmeler, Laurel;
Auchere, Frederic; Trujillo Bueno, Javier
Bibcode: 2020SPIE11444E..6WT
Altcode:
Chromospheric LAyer Spectro-Polarimeter (CLASP2) was a sounding
rocket experiment, which is a follow-up mission to the Chromospheric
Lyman-Alpha Spectro-Polarimeter (CLASP1) in 2015. To measure the
magnetic fields in the upper solar atmosphere in a highly quantitative
manner, CLASP2 changes the target wavelengths from the hydrogen Ly-α
line (121.567 nm) to Mg II lines near 280 nm. We reused the main
structure and most of the optical components in the CLASP1 instrument,
which reduced the turnaround time and cost. We added a magnifying
optical system to maintain the wavelength resolution, even at the
longer wavelength of CLASP2. Here, we describe the optical design and
performance of the CLASP2 instrument.
Title: Sunrise Chromospheric Infrared SpectroPolarimeter (SCIP)
for sunrise III: system design and capability
Authors: Katsukawa, Y.; del Toro Iniesta, J. C.; Solanki, S. K.;
Kubo, M.; Hara, H.; Shimizu, T.; Oba, T.; Kawabata, Y.; Tsuzuki,
T.; Uraguchi, F.; Nodomi, Y.; Shinoda, K.; Tamura, T.; Suematsu,
Y.; Ishikawa, R.; Kano, R.; Matsumoto, T.; Ichimoto, K.; Nagata, S.;
Quintero Noda, C.; Anan, T.; Orozco Suárez, D.; Balaguer Jiménez,
M.; López Jiménez, A. C.; Cobos Carrascosa, J. P.; Feller, A.;
Riethmueller, T.; Gandorfer, A.; Lagg, A.
Bibcode: 2020SPIE11447E..0YK
Altcode:
The Sunrise balloon-borne solar observatory carries a 1 m aperture
optical telescope and provides us a unique platform to conduct
continuous seeing-free observations at UV-visible-IR wavelengths from
an altitude of higher than 35 km. For the next flight planned for
2022, the post-focus instrumentation is upgraded with new spectro-
polarimeters for the near UV (SUSI) and the near-IR (SCIP), whereas
the imaging spectro-polarimeter Tunable Magnetograph (TuMag) is capable
of observing multiple spectral lines within the visible wavelength. A
new spectro-polarimeter called the Sunrise Chromospheric Infrared
spectroPolarimeter (SCIP) is under development for observing near-IR
wavelength ranges of around 770 nm and 850 nm. These wavelength ranges
contain many spectral lines sensitive to solar magnetic fields and
SCIP will be able to obtain magnetic and velocity structures in the
solar atmosphere with a sufficient height resolution by combining
spectro-polarimetric data of these lines. Polarimetric measurements are
conducted using a rotating waveplate as a modulator and polarizing beam
splitters in front of the cameras. The spatial and spectral resolutions
are 0.2" and 2 105, respectively, and a polarimetric sensitivity of
0.03 % (1σ) is achieved within a 10 s integration time. To detect
minute polarization signals with good precision, we carefully designed
the opto-mechanical system, polarization optics and modulation, and
onboard data processing.
Title: Detailed Calibration of the Off-Axis Optical Characteristics
for the X-Ray Telescope onboard Hinode
Authors: Shin, Junho; Sakurai, Takashi; Kano, Ryouhei; Moon, Yong-Jae;
Kim, Yeon-Han
Bibcode: 2020EGUGA..2210225S
Altcode:
The X-Ray Telescope (XRT) onboard the Hinode satellite has a
specially designed Wolter type grazing-incidence (GI) optics with a
paraboloid-hyperboloid mirror assembly to measure the solar coronal
plasma of temperatures up to 10 MK with a resolution of about one
arcsec. One of the main purposes of this scientific mission is to
investigate the detailed mechanism of energy transfer processes from the
photosphere to the upper coronal region leading to its heating and the
solar wind acceleration. To theoretically model the three-dimensional
coronal structures is sensitive to the values of plasma properties at
the base of solar corona and thus requires beforehand accurate empirical
description of those properties. Though the telescope has provided
unprecedented observations of solar corona for more than a decade,
due to a wide field of view of 34 x 34 arcmin covering the full Sun,
the optical performance of the instrument gradually deteriorates as
it goes away from the optical center. For this reason, the off-axis
characteristics of Hinode/XRT should be examined with care in order
to precisely interpret the coronal plasma properties near the solar
limb area.This presentation will explain the importance of accurate
calibration of the optical characteristics, especially for the data
taken in the off-axis region. Our previous study has shown that
the scattered light caused by the XRT mirror surface roughness has
a power-law distribution and also shows an energy dependence, with
which the PSF profile from the core to the scattering wing has been
completed. We will introduce in this study how the level of scattering
wing can be determined quantitatively for each focal plane filter from
in-flight data analysis. We have also evaluated the vignetting effect
in Hinode/XRT by analyzing the 2D distribution of effective area in
the field of view taken from MSFC/XRCF pre-launch experiment. It is
revealed that, unlike the case of Yohkoh/SXT, the degree of offset of
an optical center is not serious and thus shows little deviation from
rotational symmetry. Also important is that the vignetting pattern
in XRT shows an energy dependence, which has never been considered
before for the analyses of XRT data. More interesting results on
the calibration of Hinode/XRT scattered light and the correction of
vignetting effect will be introduced and discussed thoroughly.
Title: The Chromospheric Layer Spectro-Polarimeter (CLASP2) Sounding
Rocket Mission: First Results
Authors: McKenzie, D. E.; Ishikawa, R.; Trujillo Bueno, J.; Auchere,
F.; Rachmeler, L.; Kano, R.; Song, D.; Okamoto, J.; Kobayashi, K.;
Yoshida, M.
Bibcode: 2019AGUFMSH44A..06M
Altcode:
A major challenge for heliophysics is to decipher the magnetic structure
of the chromosphere, because of its vital role in the transport of
energy into the corona and solar wind. Routine satellite measurements
of the chromospheric magnetic field will dramatically improve our
understanding of the chromosphere and its connection to the rest of
the solar atmosphere. Before such a satellite can be considered for
flight, we must refine the measurement techniques by exploring emission
lines with a range of magnetic sensitivities. In 2015, CLASP achieved
the first measurement of linear polarization produced by scattering
processes in a far UV resonance line (hydrogen Lyman-α), and the
first exploration of the magnetic field (via the Hanle effect) and
geometrical complexity in quiet regions of the chromosphere/corona
transition region. These measurements are a first step towards
routine quantitative characterization of the local thermal and magnetic
conditions in this key layer of the solar atmosphere. Nonetheless,
Lyman-α is only one of the magnetically sensitive spectral lines in
the UV spectrum. CLASP2 extends the capability of UV spectropolarimetry
by acquiring groundbreaking measurements in the Mg II h and k spectral
lines near 280 nm, whose cores form about 100 km below the Lyman-α
core. These lines are sensitive to a larger range of field strengths
than Lyman-α, through both the Hanle and Zeeman effects. CLASP2
captures measurements of linear and circular polarization to enable
the first determination of all 4 Stokes parameters in chromospheric
UV radiation. Coupled with numerical modeling of the observed spectral
line polarization (anisotropic radiation pumping with Hanle, Zeeman and
magneto-optical effects), CLASP2 is a pathfinder for determination
of the magnetic field's strength and direction, as well as of the
geometry of the plasma in the upper solar chromosphere. CLASP2
was launched from White Sands Missile Range in April 2019. In this
presentation, we will summarize the characteristics of the CLASP2
flight, the performance of the UV telescope and spectropolarimeter,
and our preliminary findings.
Title: Center-to-Limb Variation of the polarization of Mg II h &
k lines as measured by CLASP2
Authors: Rachmeler, L.; McKenzie, D. E.; Ishikawa, R.; Kano, R.;
Trujillo Bueno, J.; Kobayashi, K.; Song, D.; Yoshida, M.; Auchere,
F.; Okamoto, J.
Bibcode: 2019AGUFMSH11D3380R
Altcode:
The Chromospheric LAyer SpectroPolarimeter 2 (CLASP2) is a sounding
rocket that was launched from White Sands Missile Range in April
2019. CLASP2 is a reflight of the CLASP instrument, and has been
modified to observe the polarization of the Magnesium II h & k
lines in the solar chromosphere. The instrument contains a slit-jaw
context imager at Lyman Alpha (~121.6nm) and two spectropolarimetric
cameras that capture Mg II h & k near 280nm. A rotating polarization
modulation unit allows us to capture the full polarization state of
Mg II h & k; the measured polarization signals are sensitive
to the Hanle and the Zeeman magnetic effects, and magneto-optical
effects. The center-to-limb variations (CLV) of the intensity of
these lines has been measured, but the CLV of the polarization signals
has only been investigated theoretically. The first flight of CLASP,
which measured the linear polarization of the Lyman alpha line, found
a surprising lack of CLV in the line core (Kano et al. 2017), which
has important implications for the magnetic strength and geometrical
complexity of the chromosphere-corona transition region (Trujillo Bueno
et al. 2018). We present here initial results on the CLV of the Mg II
polarization signals.
Title: High-frequency Wave Propagation Along a Spicule Observed
by CLASP
Authors: Yoshida, Masaki; Suematsu, Yoshinori; Ishikawa, Ryohko;
Okamoto, Takenori J.; Kubo, Masahito; Kano, Ryouhei; Narukage,
Noriyuki; Bando, Takamasa; Winebarger, Amy R.; Kobayashi, Ken;
Trujillo Bueno, Javier; Auchère, Frédéric
Bibcode: 2019ApJ...887....2Y
Altcode:
The Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP) sounding
rocket experiment, launched in 2015 September, observed the hydrogen
Lyα line (121.6 nm) in an unprecedented high temporal cadence of
0.3 s. CLASP performed sit-and-stare observations of the quiet Sun
near the limb for 5 minutes with a slit perpendicular to the limb
and successfully captured an off-limb spicule evolving along the
slit. The Lyα line is well suited for investigating how spicules
affect the corona because it is sensitive to higher temperatures than
other chromospheric lines, owing to its large optical thickness. We
found high-frequency oscillations of the Doppler velocity with periods
of 20-50 s and low-frequency oscillation of periods of ∼240 s on
the spicule. From a wavelet analysis of the time sequence data of
the Doppler velocity, in the early phase of the spicule evolution,
we found that waves with a period of ∼30 s and a velocity amplitude
of 2-3 km s-1 propagated upward along the spicule with a
phase velocity of ∼470 km s-1. In contrast, in the later
phase, possible downward and standing waves with smaller velocity
amplitudes were also observed. The high-frequency waves observed in
the early phase of the spicule evolution would be related with the
dynamics and the formation of the spicules. Our analysis enabled us to
identify the upward, downward, and standing waves along the spicule
and to obtain the velocity amplitude of each wave directly from the
Doppler velocity for the first time. We evaluated the energy flux
by the upward-propagating waves along the spicule, and discussed the
impact to the coronal heating.
Title: Design of all-reflective space-borne 1-m aperture solar
optical telescope
Authors: Suematsu, Y.; Hara, H.; Katsukawa, Y.; Kano, R.; Shimizu,
T.; Ichimoto, K.
Bibcode: 2019SPIE11180E..0RS
Altcode:
A 1-m aperture optical telescope is planned for a future Japanese solar
mission. The telescope is designed to provide high spatial resolution
data of solar lower atmosphere from the photosphere to the uppermost
chromosphere with enhanced spectroscopic and spectro-polarimetric
capabilities covering a wide wavelength region from UV to near IR where
many useful spectral lines and continua exist for physical diagnosis of
the solar magnetized atmosphere. We designed an allreflective telescope
to fulfill the scientific and engineering requirements. From a thermal
view point, a Gregorian telescope is the most suitable. To avoid
chromatic aberration, a tri-aspheric-mirror collimator coupling to
the Gregorian was designed to give a diffraction-limited performance
over the FOV by allowing a field curvature. The field curvature can
be compensated by an off-axis Ritchey Chretien reimaging optics at an
entrance of focal plane instrument, which has an opposite sign in the
field curvature to the Gregorian. We also briefly studied structural
design of all-reflective 1-m aperture solar optical telescope for the
space solar mission.
Title: The Chromospheric Layer Spectro-Polarimeter (CLASP2) Sounding
Rocket Mission: First Results
Authors: McKenzie, David Eugene; Ishikawa, Ryohko; Kano, Ryouhei;
Rachmeler, Laurel; Trujillo Bueno, Javier; Kobayashi, Ken; Song,
Donguk; Yoshida, Masaki; Auchere, Frederic; Okamoto, Takenori
Bibcode: 2019AAS...23412601M
Altcode:
A major challenge for heliophysics is to decipher the magnetic structure
of the chromosphere, because of its vital role in the transport of
energy into the corona and solar wind. Routine satellite measurements
of the chromospheric magnetic field will dramatically improve our
understanding of the chromosphere and its connection to the rest of
the solar atmosphere. Before such a satellite can be considered for
flight, we must refine the measurement techniques by exploring emission
lines with a range of magnetic sensitivities. In 2015, CLASP achieved
the first measurement of linear polarization produced by scattering
processes in a far UV resonance line (hydrogen Lyman-α), and the
first exploration of the magnetic field (via the Hanle effect) and
geometrical complexity in quiet regions of the chromosphere-corona
transition region. These measurements are a first step towards
routine quantitative characterization of the local thermal and magnetic
conditions in this key layer of the solar atmosphere. Nonetheless,
Lyman-α is only one of the magnetically sensitive spectral lines in the
UV spectrum. CLASP2 extends the capability of UV spectropolarimetry by
acquiring ground-breaking measurements in the Mg II h and k spectral
lines near 280 nm, whose cores form about 100 km below the Lyman-α
core. These lines are sensitive to a larger range of field strengths
than Lyman-α, through both the Hanle and Zeeman effects. CLASP2 will
capture measurements of linear and circular polarization to enable the
first determination of all 4 Stokes parameters in chromospheric UV
radiation. Coupled with numerical modeling of the observed spectral
line polarization (anisotropic radiation pumping with Hanle, Zeeman
and magneto-optical effects), CLASP2 is a pathfinder for determination
of the magnetic field's strength and direction, as well as of the
geometry of the plasma in the upper solar chromosphere. CLASP2
will launch from White Sands Missile Range in April 2019. In this
presentation, we will summarize the characteristics of the CLASP2
flight, the performance of the UV telescope and spectropolarimeter,
and our preliminary findings.
Title: Lyman-α imaging polarimetry with the CLASP2 sounding rocket
mission
Authors: Kano, Ryouhei; Ishikawa, Ryohko; McKenzie, David Eugene;
Trujillo Bueno, Javier; Song, Donguk; Yoshida, Masaki; Okamoto,
Takenori; Rachmeler, Laurel; Kobayashi, Ken; Auchere, Frederic
Bibcode: 2019AAS...23430216K
Altcode:
Ultraviolet polarimetry offers a unique opportunity to explore the upper
solar chromosphere and the transition region (TR) to the million-degree
corona. These outer atmospheric regions play a key role in the transfer
of mass and energy from the solar photosphere to the corona. With
a sounding rocket experiment called the Chromospheric Lyman-Alpha
Spectro-Polarimeter (CLASP), in September 2015 we succeeded in obtaining
the first measurement of the linear polarization produced by scattering
processes in the hydrogen Lyman-α line of the solar disk radiation. The
analysis and interpretation of such spectro-polarimetric observation
allowed us to obtain information on the geometrical complexity of
the corrugated surface that delineates the TR, as well as on the
magnetic field strength via the Hanle effect. At the same time, the
CLASP slit-jaw (SJ) optics system, which is a Lyman-α filter imager
characterized by a FWHM= 7 nm, allowed us to obtain broad-band Stokes-I
and Q/I images over a large field of view. The obtained broad-band
Q/I images are dominated by the scattering polarization signals of the
Lyman-α wings, and not by the much weaker line-center signals where
the Hanle effect operates. Recently, Alsina Ballester et al. (2019,
ApJ, in press) showed that the scattering polarization signals of the
Lyman-α wings are sensitive to chromospheric magnetic fields via the
magneto-optical effects. Therefore, Lyman-α imaging polarimetry is of
scientific interest also for magnetic-field investigations. On April
11, 2019, we performed another sounding rocket experiment, called
the Chromospheric LAyer Spectro-Polarimeter (CLASP2). We used the
same instrument after significant modifications in order to obtain
spectro-polarimetric observations of a plage and a quiet region in
the ionized magnesium lines around 280 nm (i.e., the Mg II h &
k lines). At the same time, the CLASP2 SJ optics system allowed us to
obtain broad-band Q/I and U/I images at the Lyman-α wavelength, in
addition to the well-known SJ intensity images. In this presentation,
we provide a first overview of the CLASP2 SJ data.
Title: Modeling the Scattering Polarization of the Hydrogen Lyα
Line Observed by CLASP in a Filament Channel
Authors: Štěpán, J.; Trujillo Bueno, J.; Gunár, S.; Heinzel, P.;
del Pino Alemán, T.; Kano, R.; Ishikawa, R.; Narukage, N.; Bando,
T.; Winebarger, A.; Kobayashi, K.; Auchère, F.
Bibcode: 2019ASPC..526..165S
Altcode:
The 400 arcsec spectrograph slit of CLASP crossed mainly quiet
regions of the solar chromosphere, from the limb towards the solar
disk center. Interestingly, in the CLASP slit-jaw images and in the
SDO images of the He II line at 304 Å, we can identify a filament
channel (FC) extending over more than 60 arcsec crossing the slit of
the spectrograph. In order to interpret the peculiar spatial variation
of the Q/I and U/I signals observed by CLASP in the hydrogen Lyα line
(1216 Å), we perform multi-dimensional radiative transfer modeling
in given filament models. In this contribution, we show the first
results of the two-dimensional calculations we have carried out, with
the aim of determining the filament thermal and magnetic structure by
comparing the theoretical and the observed polarization signals. Our
results suggest that the temperature gradients in the filament observed
by CLASP are significantly larger than previously thought.
Title: CLASP2: The Chromospheric LAyer Spectro-Polarimeter
Authors: McKenzie, D. E.; Ishikawa, R.; Trujillo Bueno, J.; Auchére,
F.; Rachmeler, L. A.; Kubo, M.; Kobayashi, K.; Winebarger, A. R.;
Bethge, C. W.; Narukage, N.; Kano, R.; Ishikawa, S.; de Pontieu,
B.; Carlsson, M.; Yoshida, M.; Belluzzi, L.; Štěpán, J.; del Pino
Alemán, T.; Alsina Ballester, E.; Asensio Ramos, A.
Bibcode: 2019ASPC..526..361M
Altcode:
The hydrogen Lyman-α line at 121.6 nm and the Mg k line at 279.5
nm are especially relevant for deciphering the magnetic structure
of the chromosphere since their line-center signals are formed in
the chromosphere and transition region, with unique sensitivities to
magnetic fields. We propose the Chromospheric LAyer Spectro-Polarimeter
(CLASP2), to build upon the success of the first CLASP flight, which
measured the linear polarization in H I Lyman-α. The existing CLASP
instrument will be refitted to measure all four Stokes parameters in
the 280 nm range, including variations due to the anisotropic radiation
pumping, the Hanle effect, and the Zeeman effect.
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 (BH) 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 BH = 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. This work, presented
in an oral contribution at this Workshop, has been published on The
Astrophysical Journal (Ishikawa et al. 2017).
Title: Determination of Large Scale Plasma Properties of Solar Corona
Using the X-Ray Telescope onboard Hinode: II. Correction for the
Scattered Lights
Authors: Shin, Junho; Kano, Ryouhei; Sakurai, Takashi; Kim, Yeon-Han;
Moon, Yong-Jae
Bibcode: 2019EGUGA..21.9726S
Altcode:
The X-Ray Telescope (XRT) onboard Hinode, which was designed to
observed a variety of coronal structures with temperature between 1
and 10 MK in the range of 34x34 arc min field of view (FOV) covering
the full solar disk, has provided solar X-ray images for more than a
decade and contributed to the progress in our understanding of coronal
physics. In particular, long-term observation of coronal hole regions
covering almost one solar cycle has an important meaning not only in
the field of solar physics but also in relation to the space weather
because the coronal hole is known as the source of solar winds. Detailed
study on the physical conditions of solar plasma in the coronal hole and
also the off-limb area will give us a clue to understand the boundary
conditions and constraints on the theoretical mechanism of heating
the coronal plasma. An astronomical telescope is in general designed
such that the best-focused image of an object is achieved at or very
close to the optical axis, and inevitably the optical performance
deteriorates away from the on-axis position. The Sun is, however, a
large astronomical object and thus targets near the limb of full-disk
images are placed at the outskirt of the field of view. Therefore,
the optical design of a solar telescope should consider with care
the uniformity of imaging quality over a wide FOV. Even after such
a design effort, the off-axis performance of the solar telescopes
should be characterized very carefully in order for the data away from
the center to be properly interpreted. We have evaluated the amount
of scattered light inherent in the Hinode/XRT data by analyzing the
in-flight images highly saturated during the solar flare events. It is
revealed that, like the case of Yohkoh/SXT, the light scattered due
to the roughness of mirror surface has a power-law distribution of
r^-2 and also shows clear energy dependence, which has enabled us to
complete a full description of XRT PSF profile from the core to the
scattering wing. A successful restoration of the scattered lights in
the observed XRT images will provide us with more precise information
on the physical quantities of solar coronal plasma in the off-limb
regions. Many interesting results on the correction for Hinode/XRT
scattered lights will be introduced and discussed thoroughly.
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: Sunrise Chromospheric Infrared spectroPolarimeter (SCIP)
for the SUNRISE balloon-borne solar observatory
Authors: Suematsu, Yoshinori; Katsukawa, Yukio; Hara, Hirohisa;
Ichimoto, Kiyoshi; Shimizu, Toshifumi; Kubo, Masahito; Barthol,
Peter; Riethmueller, Tino; Gandorfer, Achim; Feller, Alex; Orozco
Suárez, David; Del Toro Iniesta, Jose Carlos; Kano, Ryouhei; Ishikawa,
Shin-nosuke; Ishikawa, Ryohko; Tsuzuki, Toshihiro; Uraguchi, Fumihiro;
Quintero Noda, Carlos; Tamura, Tomonori; Oba, Takayoshi; Kawabata,
Yusuke; Nagata, Shinichi; Anan, Tetsu; Cobos Carrascosa, Juan Pedro;
Lopez Jimenez, Antonio Carlos; Balaguer Jimenez, Maria; Solanki, Sami
Bibcode: 2018cosp...42E3285S
Altcode:
The SUNRISE balloon-borne solar observatory carries a 1 m aperture
optical telescope, and allows us to perform seeing-free continuous
observations at visible-IR wavelengths from an altitude higher than
35 km. In the past two flights, in 2009 and 2013, observations mainly
focused on fine structures of photospheric magnetic fields. For the
third flight planned for 2021, we are developing a new instrument
for conducting spectro-polarimetry of spectral lines formed over a
larger height range in the solar atmosphere from the photosphere to
the chromosphere. Targets of the spectro-polarimetric observation
are (1) to determine 3D magnetic structure from the photosphere to
the chromosphere, (2) to trace MHD waves from the photosphere to the
chromosphere, and (3) to reveal the mechanism driving chromospheric
jets, by measuring height- and time-dependent velocities and magnetic
fields. To achieve these goals, a spectro-polarimeter called SCIP
(Sunrise Chromospheric Infrared spectroPolarimeter) is designed to
observe near-infrared spectrum lines sensitive to solar magnetic
fields. The spatial and spectral resolutions are 0.2 arcsec and
200,000, respectively, while 0.03% polarimetric sensitivity is
achieved within a 10 sec integration time. The optical system employs
an Echelle grating and off-axis aspheric mirrors to observe the two
wavelength ranges centered at 850 nm and 770 nm simultaneously by
two cameras. Polarimetric measurements are performed using a rotating
waveplate and polarization beam-splitters in front of the cameras. For
detecting minute polarization signals with good precision, we carefully
assess the temperature dependence of polarization optics, and make
the opto-structural design that minimizes the thermal deformation
of the spectrograph optics. Another key technique is to attain good
(better than 30 msec) synchronization among the rotating phase of
the waveplate, read-out timing of cameras, and step timing of a
slit-scanning mirror. On-board accumulation and data processing are
also critical because we cannot store all the raw data read-out from the
cameras. We demonstrate that we can reduce the data down to almost 10%
with loss-less image compression and without sacrificing polarimetric
information in the data. The SCIP instrument is developed by internal
collaboration among Japanese institutes including Japan Aerospace
Exploration Agency (JAXA), the Spanish Sunrise consortium, and the
German Max Planck Institute for Solar System Research (MPS) with a
leadership of the National Astronomical Observatory of Japan (NAOJ).
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: Wavefront error measurements and alignment of CLASP2 telescope
with a dual-band pass cold mirror coated primary mirror
Authors: Yoshida, Masaki; Song, Donguk; Ishikawa, Ryoko; Kano, Ryouhei;
Katsukawa, Yukio; Suematsu, Yoshinori; Narukage, Noriyuki; Kubo,
Masahito; Shinoda, Kazuya; Okamoto, Takenori J.; McKenzie, David E.;
Rachmeler, Laurel A.; Auchère, Frédéric; Trujillo Bueno, Javier
Bibcode: 2018SPIE10699E..30Y
Altcode:
"Chromospheric LAyer Spectro-Polarimeter (CLASP2)" is the next sounding
rocket experiment of the "Chromospheric Lyman-Alpha Spectro-Polarimeter
(CLASP)" that succeeded in observing for the first time the linear
polarization spectra in the hydrogen Lyman-α line (121.6 nm) and is
scheduled to be launched in 2019. In CLASP2, we will carry out full
Stokes-vector spectropolarimetric observations in the Mg ii h and k
lines near 280 nm with the spectro-polarimeter (SP), while imaging
observations in the Lyman-α line will be conducted with the slitjaw
optics (SJ). For the wavelength selection of CLASP2, the primary
mirror of the telescope uses a new dual-band pass cold mirror coating
targeting both at 121.6 nm and 280 nm. Therefore, we have to perform
again the alignment of the telescope after the installation of the
recoated primary mirror. Before unmounting the primary mirror from
the telescope structure, we measured the wave-front error (WFE) of the
telescope. The measured WFE map was consistent with what we had before
the CLASP flight, clearly indicating that the telescope alignment has
been maintained even after the flight. After the re-coated primary
mirror was installed the WFE was measured, and coma aberration was
found to be larger. Finally, the secondary mirror shim adjustments
were carried out based on the WFE measurements. In CLASP2 telescope,
we improved a fitting method of WFE map (applying 8th terms circular
Zernike polynomial fitting instead of 37th terms circular Zernike
fitting) and the improved method enables to achieve better performance
than CLASP telescope. Indeed, WFE map obtained after the final shim
adjustment indicated that the required specification (< 5.5 μm
RMS spot radius) that is more stringent than CLASP telescope was met.
Title: Optical alignment of the high-precision UV spectro-polarimeter
(CLASP2)
Authors: Song, Donguk; Ishikawa, Ryohko; Kano, Ryouhei; Yoshida,
Masaki; Tsuzuki, Toshihiro; Uraguchi, Fumihiro; Shinoda, Kazuya;
Hara, Hirohisa; Okamoto, Takenori J.; Auchère, Frédéric; McKenzie,
David E.; Rachmeler, Laurel A.; Trujillo Bueno, Javier
Bibcode: 2018SPIE10699E..2WS
Altcode:
Chromospheric LAyer Spectro-Polarimeter (CLASP2) is our next sounding
rocket experiment after the success of Chromospheric Lyman-Alpha
Spectro-Polarimeter (CLASP1). CLASP2 is scheduled to launch in 2019,
and aims to achieve high precision measurements (< 0.1 %) of the
linear and circular polarizations in the Mg ii h and k lines near the
280 nm, whose line cores originate in the upper solar chromosphere. The
CLASP2 spectro-polarimeter follows very successful design concept of
the CLASP1 instrument with the minimal modification. A new grating was
fabricated with the same radius of curvature as the CLASP1 grating, but
with a different ruling density. This allows us to essentially reuse
the CLASP1 mechanical structures and layout of the optics. However,
because the observing wavelength of CLASP2 is twice longer than that
of CLASP1, a magnifier optical system was newly added in front of the
cameras to double the focal length of CLASP2 and to maintain the same
wavelength resolution as CLASP1 (0.01 nm). Meanwhile, a careful optical
alignment of the spectro-polarimeter is required to reach the 0.01 nm
wavelength resolution. Therefore, we established an efficient alignment
procedure for the CLASP2 spectro-polarimeter based on an experience
of CLASP1. Here, we explain in detail the methods for achieving the
optical alignment of the CLASP2 spectro-polarimeter and discuss our
results by comparing with the performance requirements.
Title: Three-minute Sunspot Oscillations Driven by Magnetic
Reconnection in a Light Bridge
Authors: Song, Donguk; Chae, Jongchul; Kwak, Hannah; Kano, Ryouhei;
Yurchyshyn, Vasyl; Moon, Yong-Jae; Lim, Eun-Kyung; Lee, Jeongwoo
Bibcode: 2017ApJ...850L..33S
Altcode: 2017arXiv171106489S
We report a different type of three-minute chromospheric oscillation
above a sunspot in association with a small-scale impulsive event
in a light bridge (LB). During our observations, we found a transient
brightening in the LB. The brightening was composed of elementary bursts
that may be a manifestation of fast repetitive magnetic reconnections
in the LB. Interestingly, the oscillations in the nearby sunspot umbra
were impulsively excited when the intensity of the brightening reached
its peak. The initial period of the oscillations was about 2.3 minutes
and then gradually increased to 3.0 minutes with time. In addition,
we found that the amplitude of the excited oscillations was twice the
amplitude of oscillations before the brightening. Based on our results,
we propose that magnetic reconnection occurring in an LB can excite
oscillations in the nearby sunspot umbra.
Title: Comparison of Solar Fine Structure Observed Simultaneously
in Lyα and Mg II h
Authors: Schmit, D.; Sukhorukov, A. V.; De Pontieu, B.; Leenaarts,
J.; Bethge, C.; Winebarger, A.; Auchère, F.; Bando, T.; Ishikawa,
R.; Kano, R.; Kobayashi, K.; Narukage, N.; Trujillo Bueno, J.
Bibcode: 2017ApJ...847..141S
Altcode: 2017arXiv170900035S
The Chromospheric Lyman Alpha Spectropolarimeter (CLASP) observed the
Sun in H I Lyα during a suborbital rocket flight on 2015 September
3. The Interface Region Imaging Telescope (IRIS) coordinated with the
CLASP observations and recorded nearly simultaneous and co-spatial
observations in the Mg II h and k lines. The Mg II h and Lyα lines
are important transitions, energetically and diagnostically, in the
chromosphere. The canonical solar atmosphere model predicts that these
lines form in close proximity to each other and so we expect that the
line profiles will exhibit similar variability. In this analysis, we
present these coordinated observations and discuss how the two profiles
compare over a region of quiet Sun at viewing angles that approach the
limb. In addition to the observations, we synthesize both line profiles
using a 3D radiation-MHD simulation. In the observations, we find that
the peak width and the peak intensities are well correlated between the
lines. For the simulation, we do not find the same relationship. We
have attempted to mitigate the instrumental differences between IRIS
and CLASP and to reproduce the instrumental factors in the synthetic
profiles. The model indicates that formation heights of the lines
differ in a somewhat regular fashion related to magnetic geometry. This
variation explains to some degree the lack of correlation, observed
and synthesized, between Mg II and Lyα. Our analysis will aid in the
definition of future observatories that aim to link dynamics in the
chromosphere and transition region.
Title: CLASP/SJ Observations of Rapid Time Variations in the Lyα
Emission in a Solar Active Region
Authors: Ishikawa, Shin-nosuke; Kubo, Masahito; Katsukawa, Yukio;
Kano, Ryouhei; Narukage, Noriyuki; Ishikawa, Ryohko; Bando, Takamasa;
Winebarger, Amy; Kobayashi, Ken; Trujillo Bueno, Javier; Auchère,
Frédéric
Bibcode: 2017ApJ...846..127I
Altcode:
The Chromospheric Lyα SpectroPolarimeter (CLASP) is a sounding
rocket experiment launched on 2015 September 3 to investigate the
solar chromosphere and transition region. The slit-jaw (SJ) optical
system captured Lyα images with a high time cadence of 0.6 s. From
the CLASP/SJ observations, many variations in the solar chromosphere
and transition region emission with a timescale of <1 minute
were discovered. In this paper, we focus on the active region within
the SJ field of view and investigate the relationship between short
(<30 s) temporal variations in the Lyα emission and the coronal
structures observed by Solar Dynamics Observatory/Atmospheric Imaging
Assembly (AIA). We compare the Lyα temporal variations at the coronal
loop footpoints observed in the AIA 211 Å (≈2 MK) and AIA 171 Å
(≈0.6 MK) channels with those in the regions with bright Lyα features
without a clear association with the coronal loop footpoints. We find
more short (<30 s) temporal variations in the Lyα intensity in the
footpoint regions. Those variations did not depend on the temperature
of the coronal loops. Therefore, the temporal variations in the Lyα
intensity at this timescale range could be related to the heating of
the coronal structures up to temperatures around the sensitivity peak
of 171 Å. No signature was found to support the scenario that these
Lyα intensity variations were related to the nanoflares. Waves or
jets from the lower layers (lower chromosphere or photosphere) are
possible causes for this phenomenon.
Title: CLASP2: The Chromospheric LAyer Spectro-Polarimeter
Authors: Rachmeler, Laurel; E McKenzie, David; Ishikawa, Ryohko;
Trujillo Bueno, Javier; Auchère, Frédéric; Kobayashi, Ken;
Winebarger, Amy; Bethge, Christian; Kano, Ryouhei; Kubo, Masahito;
Song, Donguk; Narukage, Noriyuki; Ishikawa, Shin-nosuke; De Pontieu,
Bart; Carlsson, Mats; Yoshida, Masaki; Belluzzi, Luca; Stepan, Jiri;
del Pino Alemná, Tanausú; Ballester, Ernest Alsina; Asensio Ramos,
Andres
Bibcode: 2017SPD....4811010R
Altcode:
We present the instrument, science case, and timeline of the CLASP2
sounding rocket mission. The successful CLASP (Chromospheric Lyman-Alpha
Spectro-Polarimeter) sounding rocket flight in 2015 resulted in
the first-ever linear polarization measurements of solar hydrogen
Lyman-alpha line, which is sensitive to the Hanle effect and can be used
to constrain the magnetic field and geometric complexity of the upper
chromosphere. Ly-alpha is one of several upper chromospheric lines that
contain magnetic information. In the spring of 2019, we will re-fly
the modified CLASP telescope to measure the full Stokes profile of Mg
II h & k near 280 nm. This set of lines is sensitive to the upper
chromospheric magnetic field via both the Hanle and the Zeeman effects.
Title: CLASP2: The Chromospheric LAyer Spectro-Polarimeter
Authors: Rachmeler, Laurel A.; McKenzie, D. E.; Ishikawa, R.;
Trujillo-Bueno, J.; Auchere, F.; Kobayashi, K.; Winebarger, A.;
Bethge, C.; Kano, R.; Kubo, M.; Song, D.; Narukage, N.; Ishikawa, S.;
De Pontieu, B.; Carlsson, M.; Yoshida, M.; Belluzzi, L.; Stepan, J.;
del Pino Alemán, T.; Alsina Ballester, E.; Asensio Ramos, A.
Bibcode: 2017shin.confE..79R
Altcode:
We present the instrument, science case, and timeline of the CLASP2
sounding rocket mission. The successful CLASP (Chromospheric Lyman-Alpha
Spectro-Polarimeter) sounding rocket flight in 2015 resulted in
the first-ever linear polarization measurements of solar hydrogen
Lyman-alpha line, which is sensitive to the Hanle effect and can be used
to constrain the magnetic field and geometric complexity of the upper
chromosphere. Ly-alpha is one of several upper chromospheric lines that
contain magnetic information. In the spring of 2019, we will re-fly
the modified CLASP telescope to measure the full Stokes profile of Mg
II h & k near 280 nm. This set of lines is sensitive to the upper
chromospheric magnetic field via both the Hanle and the Zeeman effects.
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: High-Reflectivity Coatings for a Vacuum Ultraviolet
Spectropolarimeter
Authors: Narukage, Noriyuki; Kubo, Masahito; Ishikawa, Ryohko;
Ishikawa, Shin-nosuke; Katsukawa, Yukio; Kobiki, Toshihiko; Giono,
Gabriel; Kano, Ryouhei; Bando, Takamasa; Tsuneta, Saku; Auchère,
Frédéric; Kobayashi, Ken; Winebarger, Amy; McCandless, Jim; Chen,
Jianrong; Choi, Joanne
Bibcode: 2017SoPh..292...40N
Altcode:
Precise polarization measurements in the vacuum ultraviolet (VUV)
region are expected to be a new tool for inferring the magnetic fields
in the upper atmosphere of the Sun. High-reflectivity coatings are key
elements to achieving high-throughput optics for precise polarization
measurements. We fabricated three types of high-reflectivity coatings
for a solar spectropolarimeter in the hydrogen Lyman-α (Lyα ; 121.567
nm) region and evaluated their performance. The first high-reflectivity
mirror coating offers a reflectivity of more than 80 % in Lyα
optics. The second is a reflective narrow-band filter coating that has
a peak reflectivity of 57 % in Lyα , whereas its reflectivity in the
visible light range is lower than 1/10 of the peak reflectivity (∼5
% on average). This coating can be used to easily realize a visible
light rejection system, which is indispensable for a solar telescope,
while maintaining high throughput in the Lyα line. The third is a
high-efficiency reflective polarizing coating that almost exclusively
reflects an s-polarized beam at its Brewster angle of 68° with a
reflectivity of 55 %. This coating achieves both high polarizing power
and high throughput. These coatings contributed to the high-throughput
solar VUV spectropolarimeter called the Chromospheric Lyman-Alpha
SpectroPolarimeter (CLASP), which was launched on 3 September, 2015.
Title: Polarization Calibration of the Chromospheric Lyman-Alpha
SpectroPolarimeter for a 0.1 % Polarization Sensitivity in the VUV
Range. Part I: Pre-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.
Bibcode: 2016SoPh..291.3831G
Altcode: 2016SoPh..tmp..177G
The Chromospheric Lyman-Alpha SpectroPolarimeter (CLASP) is a sounding
rocket experiment designed to measure for the first time the linear
polarization of the hydrogen Lyman-α line (121.6 nm) and requires
a 0.1 % polarization sensitivity, which is unprecedented for a
spectropolarimeter in the vacuum UV (VUV) spectral range.
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-1, 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: Optical alignment of the Chromospheric Lyman-Alpha
Spectro-Polarimeter using sophisticated methods to minimize activities
under vacuum
Authors: Giono, G.; Katsukawa, Y.; Ishikawa, R.; Narukage, N.;
Kano, R.; Kubo, M.; Ishikawa, S.; Bando, T.; Hara, H.; Suematsu, Y.;
Winebarger, A.; Kobayashi, K.; Auchère, F.; Trujillo Bueno, J.
Bibcode: 2016SPIE.9905E..3DG
Altcode:
The Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP) is a
sounding-rocket instrument developed at the National Astronomical
Observatory of Japan (NAOJ) as a part of an international
collaboration. The instrument main scientific goal is to achieve
polarization measurement of the Lyman-α line at 121.56 nm emitted from
the solar upper-chromosphere and transition region with an unprecedented
0.1% accuracy. The optics are composed of a Cassegrain telescope
coated with a "cold mirror" coating optimized for UV reflection and
a dual-channel spectrograph allowing for simultaneous observation of
the two orthogonal states of polarization. Although the polarization
sensitivity is the most important aspect of the instrument, the spatial
and spectral resolutions of the instrument are also crucial to observe
the chromospheric features and resolve the Ly-α profiles. A precise
alignment of the optics is required to ensure the resolutions, but
experiments under vacuum conditions are needed since Ly-α is absorbed
by air, making the alignment experiments difficult. To bypass this
issue, we developed methods to align the telescope and the spectrograph
separately in visible light. We explain these methods and present
the results for the optical alignment of the CLASP telescope and
spectrograph. We then discuss the combined performances of both parts
to derive the expected resolutions of the instrument, and compare them
with the flight observations performed on September 3rd 2015.
Title: Chromospheric LAyer SpectroPolarimeter (CLASP2)
Authors: Narukage, Noriyuki; McKenzie, David E.; Ishikawa, Ryoko;
Trujillo-Bueno, Javier; De Pontieu, Bart; Kubo, Masahito; Ishikawa,
Shin-nosuke; Kano, Ryouhei; Suematsu, Yoshinori; Yoshida, Masaki;
Rachmeler, Laurel A.; Kobayashi, Ken; Cirtain, Jonathan W.; Winebarger,
Amy R.; Asensio Ramos, Andres; del Pino Aleman, Tanausu; Štępán,
Jiri; Belluzzi, Luca; Larruquert, Juan Ignacio; Auchère, Frédéric;
Leenaarts, Jorrit; Carlsson, Mattias J. L.
Bibcode: 2016SPIE.9905E..08N
Altcode:
The sounding rocket Chromospheric Lyman-Alpha SpectroPolarimeter
(CLASP) was launched on September 3rd, 2015, and successfully detected
(with a polarization accuracy of 0.1 %) the linear polarization signals
(Stokes Q and U) that scattering processes were predicted to produce
in the hydrogen Lyman-alpha line (Lyα 121.567 nm). Via the Hanle
effect, this unique data set may provide novel information about the
magnetic structure and energetics in the upper solar chromosphere. The
CLASP instrument was safely recovered without any damage and we have
recently proposed to dedicate its second flight to observe the four
Stokes profiles in the spectral region of the Mg II h and k lines
around 280 nm; in these lines the polarization signals result from
scattering processes and the Hanle and Zeeman effects. Here we describe
the modifications needed to develop this new instrument called the
"Chromospheric LAyer SpectroPolarimeter" (CLASP2).
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 a Precise Polarization Modulator for UV
Spectropolarimetry
Authors: Ishikawa, S.; Shimizu, T.; Kano, R.; Bando, T.; Ishikawa,
R.; Giono, G.; Tsuneta, S.; Nakayama, S.; Tajima, T.
Bibcode: 2015SoPh..290.3081I
Altcode: 2015arXiv150905716I; 2015SoPh..tmp..120I
We developed a polarization modulation unit (PMU) to rotate a
waveplate continuously in order to observe solar magnetic fields
by spectropolarimetry. The non-uniformity of the PMU rotation may
cause errors in the measurement of the degree of linear polarization
(scale error) and its angle (crosstalk between Stokes-Q and -U ),
although it does not cause an artificial linear polarization signal
(spurious polarization). We rotated a waveplate with the PMU to obtain
a polarization modulation curve and estimated the scale error and
crosstalk caused by the rotation non-uniformity. The estimated scale
error and crosstalk were <0.01 % for both. This PMU will be used as
a waveplate motor for the Chromospheric Lyman-Alpha SpectroPolarimeter
(CLASP) rocket experiment. We confirm that the PMU performs and
functions sufficiently well for CLASP.
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: Strategy for Realizing High-Precision VUV Spectro-Polarimeter
Authors: Ishikawa, R.; Narukage, N.; Kubo, M.; Ishikawa, S.; Kano,
R.; Tsuneta, S.
Bibcode: 2014SoPh..289.4727I
Altcode: 2014SoPh..tmp..116I
Spectro-polarimetric observations in the vacuum ultraviolet (VUV)
range are currently the only means to measure magnetic fields in the
upper chromosphere and transition region of the solar atmosphere. The
Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP) aims to measure
linear polarization at the hydrogen Lyman-α line (121.6 nm). This
measurement requires a polarization sensitivity better than 0.1 %,
which is unprecedented in the VUV range. We here present a strategy with
which to realize such high-precision spectro-polarimetry. This involves
the optimization of instrument design, testing of optical components,
extensive analyses of polarization errors, polarization calibration
of the instrument, and calibration with onboard data. We expect that
this strategy will aid the development of other advanced high-precision
polarimeters in the UV as well as in other wavelength ranges.
Title: Precision VUV Spectro-Polarimetry for Solar Chromospheric
Magnetic Field Measurements
Authors: Ishikawa, R.; Bando, T.; Hara, H.; Ishikawa, S.; Kano, R.;
Kubo, M.; Katsukawa, Y.; Kobiki, T.; Narukage, N.; Suematsu, Y.;
Tsuneta, S.; Aoki, K.; Miyagawa, K.; Ichimoto, K.; Kobayashi, K.;
Auchère, F.; Clasp Team
Bibcode: 2014ASPC..489..319I
Altcode:
The Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP) is a VUV
spectro-polarimeter optimized for measuring the linear polarization
of the Lyman-α line (121.6 nm) to be launched in 2015 with NASA's
sounding rocket (Ishikawa et al. 2011; Narukage et al. 2011; Kano et
al. 2012; Kobayashi et al. 2012). With this experiment, we aim to (1)
observe the scattering polarization in the Lyman-α line, (2) detect
the Hanle effect, and (3) assess the magnetic fields in the upper
chromosphere and transition region for the first time. The polarization
measurement error consists of scale error δ a (error in amplitude
of linear polarization), azimuth error Δφ (error in the direction
of linear polarization), and spurious polarization ɛ (false linear
polarization signals). The error ɛ should be suppressed below 0.1%
in the Lyman-α core (121.567 nm ±0.02 nm), and 0.5% in the Lyman-α
wing (121.567 nm ±0.05 nm), based on our scientific requirements shown
in Table 2 of Kubo et al. (2014). From scientific justification, we
adopt Δ φ<2° and δ a<10% as the instrument requirements. The
spectro-polarimeter features a continuously rotating MgF2
waveplate (Ishikawa et al. 2013), a dual-beam spectrograph with a
spherical grating working also as a beam splitter, and two polarization
analyzers (Bridou et al. 2011), which are mounted at 90 degree from
each other to measure two orthogonal polarization simultaneously. For
the optical layout of the CLASP instrument, see Figure 3 in Kubo et
al. (2014). Considering the continuous rotation of the half-waveplate,
the modulation efficiency is 0.64 both for Stokes Q and U. All the raw
data are returned and demodulation (successive addition or subtraction
of images) is done on the ground. We control the CLASP polarization
performance in the following three steps. First, we evaluate the
throughput and polarization properties of each optical component in
the Lyman-α line, using the Ultraviolet Synchrotron ORbital Radiation
Facility (UVSOR) at the Institute for Molecular Science. The second
step is polarization calibration of the spectro-polarimeter after
alignment. Since the spurious polarization caused by the axisymmetric
telescope is estimated to be negligibly small because of the symmetry
(Ishikawa et al. 2014), we do not perform end-to-end polarization
calibration. As the final step, before the scientific observation near
the limb, we make a short observation at the Sun center and verify
the polarization sensitivity, because the scattering polarization
is expected to be close to zero at the Sun center due to symmetric
geometry. In order to clarify whether we will be able to achieve the
required polarization sensitivity and accuracy via these steps, we
exercise polarization error budget, by investigating all the possible
causes and their magnitudes of polarization errors, all of which are not
necessarily verified by the polarization calibration. Based on these
error budgets, we conclude that a polarization sensitivity of 0.1% in
the line core, δ a<10% and Δ φ<2° can be achieved combined
with the polarization calibration of the spectro-polarimeter and the
onboard calibration at the Sun center(refer to Ishikawa et al. 2014,
for the detail). We are currently conducting verification tests
of the flight components and development of the UV light source for
the polarization calibration. From 2014 spring, we will begin the
integration, alignment, and calibration. We will update the error
budgets throughout the course of these tests.
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: Large aperture solar optical telescope and instruments for
the SOLAR-C mission
Authors: Suematsu, Y.; Katsukawa, Y.; Hara, H.; Kano, R.; Shimizu,
T.; Ichimoto, K.
Bibcode: 2014SPIE.9143E..1PS
Altcode:
A large aperture solar optical telescope and its instruments
for the SOLAR-C mission are under study to provide the critical
physical parameters in the lower solar atmosphere and to resolve the
mechanism of magnetic dynamic events happening there and in the upper
atmosphere as well. For the precise magnetic field measurements and
high angular resolution in wide wavelength region, covering FOV of 3
arcmin x3 arcmin, an entrance aperture of 1.4 m Gregorian telescope is
proposed. Filtergraphs are designed to realize high resolution imaging
and pseudo 2D spectro-polarimetry in several magnetic sensitive lines of
both photosphere and chromosphere. A full stokes polarimetry is carried
out at three magnetic sensitive lines with a four-slit spectrograph
of 2D image scanning mechanism. We present a progress in optical and
structural design of SOLAR-C large aperture optical telescope and its
observing instruments which fulfill science requirements.
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: 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: Photospheric Properties of Warm EUV Loops and Hot X-Ray Loops
Authors: Kano, R.; Ueda, K.; Tsuneta, S.
Bibcode: 2014ApJ...782L..32K
Altcode:
We investigate the photospheric properties (vector magnetic fields and
horizontal velocity) of a well-developed active region, NOAA AR 10978,
using the Hinode Solar Optical Telescope specifically to determine
what gives rise to the temperature difference between "warm loops"
(1-2 MK), which are coronal loops observed in EUV wavelengths, and
"hot loops" (>3 MK), coronal loops observed in X-rays. We found
that outside sunspots, the magnetic filling factor in the solar network
varies with location and is anti-correlated with the horizontal random
velocity. If we accept that the observed magnetic features consist of
unresolved magnetic flux tubes, this anti-correlation can be explained
by the ensemble average of flux-tube motion driven by small-scale random
flows. The observed data are consistent with a flux tube width of ~77
km and horizontal flow at ~2.6 km s-1 with a spatial scale
of ~120 km. We also found that outside sunspots, there is no significant
difference between warm and hot loops either in the magnetic properties
(except for the inclination) or in the horizontal random velocity
at their footpoints, which are identified with the Hinode X-Ray
Telescope and the Transition Region and Coronal Explorer. The energy
flux injected into the coronal loops by the observed photospheric
motion of the magnetic fields is estimated to be 2 × 106
erg s-1 cm-2, which is the same for both warm and
hot loops. This suggests that coronal properties (e.g., loop length)
play a more important role in giving rise to temperature differences
of active-region coronal loops than photospheric parameters.
Title: Chromospheric Lyman-alpha spectro-polarimeter (CLASP)
Authors: Kano, Ryouhei; Katsukawa, Yukio; Kubo, Masahito; Auchere,
Frederic; Ishikawa, Ryohko; Kobayashi, Ken; Narukage, Noriyuki;
Trujillo Bueno, Javier; Bando, Takamasa; Ishikawa, Shin-nosuke
Bibcode: 2014cosp...40E1383K
Altcode:
In the solar chromosphere, magneto-hydrodynamic waves and super-sonic
jets ubiquitously happen as revealed by the Japanese solar satellite
Hinode. Now, we understand that the solar chromosphere is not a simple
intermediate layer smoothly connecting the photosphere and corona,
but a site where those dynamics may play an important role in the
chromospheric and coronal heating. Such discoveries imply that the
next frontier in solar physics lies in simultaneous observations
between the dynamics and magnetic structures in the chromosphere and
transition region, where the gas-dominant photosphere changes to the
magnetic-dominant corona. Therefore, we promote the Chromospheric
Lyman-Alpha SpectroPolarimeter (CLASP), which is a NASA's sounding
rocket experiment scheduled in 2015 for aiming to infer the magnetic
field information in the solar chromosphere and transition region. CLASP
makes precise measurement (0.1%) of the polarization profile of the
Lyman-alpha line, and aims to make the first ever measurement of the
Hanle effect polarization caused by magnetic fields in the upper solar
atmosphere. It is also a pathfinder to establish a new measurement
tool for chromospheric and transition-region magnetic fields, and to
make progress on chromospheric studies in future missions.
Title: UV spectropolarimeter design for precise polarization
measurement and its application to the CLASP for exploration of
magnetic fields in solar atmosphere
Authors: Narukage, Noriyuki; Katsukawa, Yukio; Hara, Hirohisa; Kubo,
Masahito; Auchere, Frederic; Ishikawa, Ryohko; Kano, Ryouhei; Bando,
Takamasa; Ishikawa, Shin-nosuke; Suematsu, Yoshinori; Tsuneta, Saku
Bibcode: 2014cosp...40E2232N
Altcode:
In order to measure the magnetic field in the region where the
hot plasma from 10 (4) K to 10 (6) K is occupied, e.g., for solar
atmosphere, the polarimetric measurements in ultra violet (UV)
with 0.1% accuracy are required. In this paper, we propose a new
UV spectropolarimeter design with 0.1% sensitivity in polarization
measurement. This spectropolarimeter has two devices for the 0.1%
accuracy. First, all optical components except the waveplate are the
reflective type ones that can be equipped with the high reflectivity
coating for the high throughput. Secondly, it equips the optically
symmetric dual channels to measure the orthogonal linear polarization
state simultaneously, using a concave diffraction grating as both the
spectral dispersion element and the beam splitter. These two devices
make the spurious polarizations caused by the photon noise, by the
intensity variation of the observation target, and, by the instrument
itself, enough small to achieve the 0.1% accuracy in polarization
measurement. The spectropolarimeter thus designed is currently under
fabrication for the sounding rocket project of Chromospheric Lyman-Alpha
SpectroPolarimeter (CLASP) that aims at the direct measurement of the
magnetic fields in solar atmosphere with Lyman-alpha line (121.6 nm)
for the first time.
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: 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 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. 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: Nanoflare Evidence from Analysis of the X-Ray Variability of
an Active Region Observed with Hinode/XRT
Authors: Terzo, S.; Reale, F.; Miceli, M.; Kano, R.; Tsuneta, S.;
Klimchuk, J. A.
Bibcode: 2012ASPC..455..245T
Altcode: 2012arXiv1201.5482T
The heating of the solar corona is one of the big questions in
astrophysics. Rapid pulses called nanoflares are among the best
candidate mechanisms. The analysis of the time variability of coronal
X-ray emission is potentially a very useful tool to detect impulsive
events. We analyze the small-scale variability of a solar active
region in a high cadence Hinode/XRT observation. The dataset allows
us to detect very small deviations of emission fluctuations from the
distribution expected for a constant rate. We discuss the deviations
in the light of the pulsed-heating scenario.
Title: Thermal Properties of a Solar Coronal Cavity Observed with
the X-Ray Telescope on Hinode
Authors: Reeves, Katharine K.; Gibson, Sarah E.; Kucera, Therese A.;
Hudson, Hugh S.; Kano, Ryouhei
Bibcode: 2012ApJ...746..146R
Altcode:
Coronal cavities are voids in coronal emission often observed above
high latitude filament channels. Sometimes, these cavities have areas of
bright X-ray emission in their centers. In this study, we use data from
the X-ray Telescope (XRT) on the Hinode satellite to examine the thermal
emission properties of a cavity observed during 2008 July that contains
bright X-ray emission in its center. Using ratios of XRT filters, we
find evidence for elevated temperatures in the cavity center. The area
of elevated temperature evolves from a ring-shaped structure at the
beginning of the observation, to an elongated structure two days later,
finally appearing as a compact round source four days after the initial
observation. We use a morphological model to fit the cavity emission,
and find that a uniform structure running through the cavity does not
fit the observations well. Instead, the observations are reproduced
by modeling several short cylindrical cavity "cores" with different
parameters on different days. These changing core parameters may be
due to some observed activity heating different parts of the cavity
core at different times. We find that core temperatures of 1.75 MK,
1.7 MK, and 2.0 MK (for July 19, July 21, and July 23, respectively)
in the model lead to structures that are consistent with the data,
and that line-of-sight effects serve to lower the effective temperature
derived from the filter ratio.
Title: Ly-alpha polarimeter design for CLASP rocket experiment
Authors: Kubo, M.; Watanabe, H.; Narukage, N.; Ishikawa, R.; Bando,
T.; Kano, R.; Tsuneta, S.; Kobayashi, K.; Ichimoto, K.; Trujillo Bueno,
J.; Song, D.
Bibcode: 2011AGUFM.P11F1627K
Altcode:
A sounding-rocket program called the Chromospheric Lyman-Alpha
Spectro-Polarimeter (CLASP) is proposed to be launched in the Summer
of 2014. CLASP will observe the upper solar chromosphere in Ly-alpha
(121.567 nm), aiming to detect the linear polarization signal produced
by scattering processes and the Hanle effect for the first time. The
CLASP needs a rotating half-waveplate and a polarization analyzer
working at the Ly-alpha wavelength to measure the linear polarization
signal. We select Magnesium Fluoride (MgF2) as a material of the
optical components because of its birefringent property and high
transparency at UV wavelength. We have confirmed that the reflection
at the Brewster's Angle of MgF2 plate is a good polarization analyzer
for the Ly-alpha line by deriving its ordinary refractive index and
extinction coefficient along the ordinary and extraordinary axes. These
optical parameters are calculated with a least-square fitting in such a
way that the reflectance and transmittance satisfy the Kramers-Kronig
relation. The reflectance and transmittance against oblique incident
angles for the s-polarized and the p-polarized light are measured
using the synchrotron beamline at the Ultraviolet Synchrotron Orbital
Radiation Facility (UVSOR). We have also measured a retardation of
a zeroth-order waveplate made of MgF2. The thickness difference of
the waveplate is 14.57 um.This waveplate works as a half-waveplate at
121.74 nm. From this measurement, we estimate that a waveplate with
the thickness difference of 15.71 um will work as a half-waveplate
at the Ly-alpha wavelength. We have developed a rotating waveplate -
polarization analyzer system called a prototype of CLASP polarimeter,
and input the perfect Stokes Q and U signals. The modulation patterns
that are consistent with the theoretical prediction are successfully
obtained in both cases.
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: Ly-alpha polarimeter design for CLASP rocket experiment
Authors: Watanabe, H.; Narukage, N.; Kubo, M.; Ishikawa, R.; Bando, T.;
Kano, R.; Tsuneta, S.; Kobayashi, K.; Ichimoto, K.; Trujillo-Bueno, J.
Bibcode: 2011SPIE.8148E..0TW
Altcode: 2011SPIE.8148E..25W; 2014arXiv1407.4577W
A sounding-rocket program called the Chromospheric Lyman-Alpha
Spectro-Polarimeter (CLASP) is proposed to be launched in the summer of
2014. CLASP will observe the solar chromosphere in Ly-alpha (121.567
nm), aiming to detect the linear polarization signal produced by
scattering processes and the Hanle effect for the first time. The
polarimeter of CLASP consists of a rotating half-waveplate, a beam
splitter, and a polarization analyzer. Magnesium Fluoride (MgF2) is
used for these optical components, because MgF2 exhibits birefringent
property and high transparency at ultraviolet wavelength. The
development and comprehensive testing program of the optical components
of the polarimeter is underway using the synchrotron beamline at the
Ultraviolet Synchrotron Orbital Radiation Facility (UVSOR). The first
objective is deriving the optical constants of MgF2 by the measurement
of the reflectance and transmittance against oblique incident angles
for the s-polarized and the p-polarized light. The ordinary refractive
index and extinction coefficient along the ordinary and extraordinary
axes are derived with a least-square fitting in such a way that the
reflectance and transmittance satisfy the Kramers-Krönig relation. The
reflection at the Brewster's Angle of MgF2 plate is confirmed to become
a good polarization analyzer at Ly-alpha. The second objective is the
retardation measurement of a zeroth-order waveplate made of MgF2. The
retardation of a waveplate is determined by observing the modulation
amplitude that comes out of a waveplate and a polarization analyzer. We
tested a waveplate with the thickness difference of 14.57 um. The 14.57
um waveplate worked as a half-waveplate at 121.74 nm. We derived that
a waveplate with the thickness difference of 15.71 um will work as a
half-waveplate at Ly-alpha wavelength. We developed a prototype of CLASP
polarimeter using the MgF2 half-waveplate and polarization analyzers,
and succeeded in obtaining the modulation patterns that are consistent
with the theoretical prediction. We confirm that the performance of
the prototype is optimized for measuring linear polarization signal
with the least effect of the crosstalk from the circular polarization.
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: Widespread Nanoflare Variability Detected with Hinode/X-Ray
Telescope in a Solar Active Region
Authors: Terzo, Sergio; Reale, Fabio; Miceli, Marco; Klimchuk, James
A.; Kano, Ryouhei; Tsuneta, Saku
Bibcode: 2011ApJ...736..111T
Altcode: 2011arXiv1105.2506T
It is generally agreed that small impulsive energy bursts called
nanoflares are responsible for at least some of the Sun's hot corona,
but whether they are the explanation for most of the multimillion-degree
plasma has been a matter of ongoing debate. We present here evidence
that nanoflares are widespread in an active region observed by the X-Ray
Telescope on board the Hinode mission. The distributions of intensity
fluctuations have small but important asymmetries, whether taken
from individual pixels, multipixel subregions, or the entire active
region. Negative fluctuations (corresponding to reduced intensity)
are greater in number but weaker in amplitude, so that the median
fluctuation is negative compared to a mean of zero. Using Monte Carlo
simulations, we show that only part of this asymmetry can be explained
by Poisson photon statistics. The remainder is explainable through
a tendency for exponentially decreasing intensity, such as would be
expected from a cooling plasma produced from a nanoflare. We suggest
that nanoflares are a universal heating process within active regions.
Title: A Sounding Rocket Experiment for Spectropolarimetric
Observations with the Lyα Line at 121.6 nm (CLASP)
Authors: Ishikawa, R.; Bando, T.; Fujimura, D.; Hara, H.; Kano,
R.; Kobiki, T.; Narukage, N.; Tsuneta, S.; Ueda, K.; Wantanabe,
H.; Kobayashi, K.; Trujillo Bueno, J.; Manso Sainz, R.; Stepan, J.;
de Pontieu, B.; Carlsson, M.; Casini, R.
Bibcode: 2011ASPC..437..287I
Altcode:
A team consisting of Japan, USA, Spain, and Norway is developing a
high-throughput Chromospheric Lyman-Alpha SpectroPolarimeter (CLASP),
which is proposed to fly with a NASA sounding rocket in 2014. CLASP will
explore the magnetism of the upper solar chromosphere and transition
region via the Hanle effect of the Lyα line for the first
time. This experiment requires spectropolarimetric observations with
high polarimetric sensitivity (∼0.1%) and wavelength resolution
(0.1 Å). The final spatial resolution (slit width) is being discussed
taking into account the required high signal-to-noise ratio. We have
demonstrated the performance of the Lyα polarimeter by
extensively using the Ultraviolet Synchrotron ORbital Radiation Facility
(UVSOR) at the Institute for Molecular Sciences. In this contribution,
we report these measurements at UVSOR together with the current status
of the CLASP project.
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: Hinode Observation of Photospheric Magnetic Activities
Triggering X-ray Microflares Around a Well-developed Sunspot
Authors: Kano, R.; Shimizu, T.; Tarbell, T. D.
Bibcode: 2010ApJ...720.1136K
Altcode:
Microflares, which are small energetic events in the solar corona, are
an example of dynamical phenomena suitable for understanding energy
release processes in the solar corona. We identified 55 microflares
around a well-developed sunspot surrounded by a moat with high-cadence
X-ray images from the Hinode X-ray Telescope, and searched for their
photospheric counterparts in line-of-sight magnetograms taken with the
Hinode Solar Optical Telescope. We found opposite magnetic polarities
encountering each other around the footpoints of 28 microflares,
while we could not find such encounters around the footpoints of the
other 27 microflares. Emerging magnetic fluxes in the moat were the
dominant origin causing the encounters of opposite polarities (21 of
28 events). Unipolar moving magnetic features (MMFs) with negative
polarities the same as the sunspot definitely caused the encounters of
opposite polarities for five microflares. The decrease of magnetic flux,
i.e., magnetic flux cancellation, was confirmed at the encountering site
in typical examples of microflares. Microflares were not isotropically
distributed around the spot; the microflares with emerging magnetic
fluxes (EMFs) were observed in the direction where magnetic islands
with the same polarity as the spot were located at the outer boundary
of the moat, while the microflares with negative MMFs were observed
in the direction where magnetic islands with polarity opposite to the
spot were located at the outer boundary of the moat. We also found that
EMFs in the moat had a unique orientation in which those with the same
polarity as the spot is closer to the spot than the other one that had
the opposite polarity to the spot. These observational results lead
to two magnetic configurations including magnetic reconnection for
triggering energy release at least in half of the microflares around
the spot, and suggest that the global magnetic structures around the
spot strongly affect what kinds of polarity encounters are formed in
the sunspot moat.
Title: Orientation of X-Ray Bright Points in the Quiet Sun
Authors: Ueda, K.; Kano, R.; Tsuneta, S.; Shibahashi, H.
Bibcode: 2010SoPh..261...77U
Altcode:
Thanks to the high-resolution images from the X-ray telescope (XRT)
aboard the Hinode satellite, X-ray bright points (XBPs) in the quiet
region of the Sun are resolved and can be seen to have complex loop-like
structures. We measure the orientation of such loop structures for 488
XBPs picked up in 26 snapshot X-ray images near the disk center. The
distribution of the orientation is slightly but clearly biased to
the east - west direction: the random distribution is rejected with a
significance level of 1% by the χ2-test. The distribution
is similar to the orientation distribution for the bipolar magnetic
fields. The XBP orientation is, however, much more random than that
of the bipolar magnetic fields with similar size. 24% of the XBPs are
due to emerging bipoles, while the remaining 76% are due to chance
encounters of opposite polarities.
Title: Analysis of the X-ray variability of an active region observed
with Hinode/XRT for investigation of coronal heating
Authors: Terzo, Sergio; Tsuneta, Saku; Kano, Ryouhei; Miceli, Marco;
Reale, Fabio
Bibcode: 2010cosp...38.2898T
Altcode: 2010cosp.meet.2898T
Impulsive mechanisms of solar and stellar coronal heating are under
investigation. The analysis of the time variability of coronal emission
is one of the useful tools. We analyze the small-scale variability of a
solar active region in a high cadence Hinode/XRT observation. We compare
measured fluctuation intensity distributions with the distribution
expected for Poisson noise and look for possible signatures of
nanoflaring activity, which might be extrapolated to stellar coronae.
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: 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: 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
1025.5-1026.0cm-5. 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 < 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: Co-alignment
with SOT and EIS Spot removal for dynamics studies Filter calibration
for thermal studies Dark calibrations Sample data sets will be
discussed and links to the data products will be provided.
Title: Molecular Contamination Assessments on
<i>Hinode</i> X-Ray Telescope
Authors: Urayama, Fumitaka; Bando, Takamasa; Kano, Ryouhei; Hara,
Hirohisa; Narukage, Noriyuki; Sakao, Taro
Bibcode: 2008JSASS..56..536U
Altcode:
The <i>Hinode</i> (Solar-B) was launched by M-V rocket on 22
September 2006 UT. The telemetry data of the <i>Hinode</i>
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: Multiplicity of Solar X-Ray Corona in Time and Space
Authors: Kano, R.; XRT Team
Bibcode: 2008PFR.....2S1010K
Altcode:
The Soft X-ray Telescope (XRT) aboard the Hinode satellite is a grazing
incidence X-ray telescope equipped with 2 k × 2 k CCD. XRT has 1
arcsec resolution with wide field-of-view of 34 × 34 arcmin. It is
sensitive to < 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 is 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: 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: 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 × 103 to
2 × 104 kilometers wide and 1 × 105 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-1 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-1 for the outward
velocity, 5 × 104 km for the height, 8 × 103
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-1. 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: 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 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. 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. 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). 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 × 109 /cm3. Assuming that all the material
is to escape to the interplanetary space, this leads to a mass loss
rate of 2 × 1011 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. 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. 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: Tolerance test of a sample filter for use in space
Authors: Hayashi, Masao; Tanaka, Mikito; Komiyama, Yutaka; Okamura,
Sadanori; Tsuneta, Saku; Noguchi, Motokazu; Nakagiri, Masao; Kano,
Ryouhei; Kimura, Toshihiko
Bibcode: 2006PNAOJ...9...21H
Altcode:
We report the result of a tolerance test of a sample filter for the
planned Very Wide Field Imager on board the Hubble Origin Probe. We
investigated whether the properties of the filter and its components,
i.e., color glass, synthetic quartz, short-wavelength-pass coating
and long-wavelength-pass coating, changed after they were put in a
vacuum, after they were subjected to a thermal cycle, and after they
were exposed to γ ray. Results are shown mostly in graphical form. No
significant change of the properties was observed for the filter and
any of the components before and after the tests, except for the color
glass which was exposed to strong γ ray.
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: 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
<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: 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: 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: Evolution of the High Temperature Corona
Authors: Kano, R.
Bibcode: 2004cosp...35.4441K
Altcode: 2004cosp.meet.4441K
Yohkoh meticulously observed the solar corona for more than 10 years
from 1991 to the accidental termination in December 2001. Yohkoh
shows that any transients, such as flares and micro-flares, are due
to magnetic reconnection in the form of cusp or loop-loop interactions
without exception, while the heating mechanism for the more stationary
corona, the energy content of which is much more dominant than that
of the transients, remains totally unknown. Hot SXT loops have the
highest temperature and emission measure (inverted corona) near
the loop top, while cool TRACE loops appear to have more uniform
temperature. These hot and cool loops reflect differences in the heat
input rate across the loops as well along the loops. The question is
whether these loops are heated by nano-flares, and (if the answer is
yes) how they create the multi-temperature corona as observed. Reaching
the detection limit in the hunting of smaller and smaller events, we
stress the importance of X-ray intensity fluctuations, which contain
information on pico-flares. Another mystery on longer time scale is
that the overall intensity of the quiet-Sun X-ray corona appears to
change with solar cycle: basal heating is modulated by the magnetic
solar cycle, while the number of X-ray bright points is surprisingly
constant over the solar cycle against previous observations.
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>1 MK) temperature evolution of coronal loops. The
detailed morphological comparison of an active region shows that hot
loops seen in SXT (T>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: The Temperature Analysis of Yohkoh/SXT Data using the CHIANTI
Spectral Database
Authors: Shimojo, M.; Hara, H.; Kano, R.
Bibcode: 2002mwoc.conf..419S
Altcode:
Since the CHIANTI database for astrophysical emission line spectroscopy
was extended to X-ray wavelengths below 50Å recently (Dere et
al. 2000), a temperature response of YOHKOH/SXT has been able to
calculate using the database. The functions of temperature responses of
SXT are very important for plasma diagnostic since we usually derive
the electron temperature of coronal plasma using the observed signal
counts and the ratio of the temperature responses. In this paper,
we present the properties of the SXT temperature responses which are
calculated from the CHIANTI database and also compare them with the
SXT temperature responses which are calculated using Mewe spectral
databases (Mewe, et al., 1985, 1986). We calculated the filter ratios
using CHIANTI database and compared them with the filter ratios which
are calculated from Mewe database. At the result, it is found that
the difference between temperatures which are derived using CHIANTI
and Mewe database is about 2 MK around 5 MK, if we use Al and Al12
filters for the plasma diagnostic. The result is the same as Schmelz
et al.(1999). In the paper, we also discuss the effect of the CHIANTI
spectral databases for previous works which used the filter ratios
based on Mewe database.
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: 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&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: 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&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 (>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&ring
line indicates a possible down-flow of 1.8 MK plasma near the footpoints
of multiple cool loops
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: Erratum: Temperature Distributions and Energy Scaling Law of
Solar Coronal Loops Obtained with Yohkoh
Authors: Kano, Ryouhei; Tsuneta, Saku
Bibcode: 1999PASJ...51..569K
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: 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: 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: 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