Author name code: delaboudiniere
ADS astronomy entries on 2022-09-14
author:"Delaboudiniere, Jean-Pierre"
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Title: Sun Earth Connection Coronal and Heliospheric Investigation
(SECCHI)
Authors: Howard, R. A.; Moses, J. D.; Vourlidas, A.; Newmark, J. S.;
Socker, D. G.; Plunkett, S. P.; Korendyke, C. M.; Cook, J. W.; Hurley,
A.; Davila, J. M.; Thompson, W. T.; St Cyr, O. C.; Mentzell, E.;
Mehalick, K.; Lemen, J. R.; Wuelser, J. P.; Duncan, D. W.; Tarbell,
T. D.; Wolfson, C. J.; Moore, A.; Harrison, R. A.; Waltham, N. R.;
Lang, J.; Davis, C. J.; Eyles, C. J.; Mapson-Menard, H.; Simnett,
G. M.; Halain, J. P.; Defise, J. M.; Mazy, E.; Rochus, P.; Mercier,
R.; Ravet, M. F.; Delmotte, F.; Auchere, F.; Delaboudiniere, J. P.;
Bothmer, V.; Deutsch, W.; Wang, D.; Rich, N.; Cooper, S.; Stephens,
V.; Maahs, G.; Baugh, R.; McMullin, D.; Carter, T.
Bibcode: 2008SSRv..136...67H
Altcode: 2008SSRv..tmp...64H
The Sun Earth Connection Coronal and Heliospheric Investigation
(SECCHI) is a five telescope package, which has been developed for
the Solar Terrestrial Relation Observatory (STEREO) mission by the
Naval Research Laboratory (USA), the Lockheed Solar and Astrophysics
Laboratory (USA), the Goddard Space Flight Center (USA), the University
of Birmingham (UK), the Rutherford Appleton Laboratory (UK), the
Max Planck Institute for Solar System Research (Germany), the Centre
Spatiale de Leige (Belgium), the Institut d’Optique (France) and the
Institut d’Astrophysique Spatiale (France). SECCHI comprises five
telescopes, which together image the solar corona from the solar disk to
beyond 1 AU. These telescopes are: an extreme ultraviolet imager (EUVI:
1 1.7 R⊙), two traditional Lyot coronagraphs (COR1: 1.5 4
R⊙ and COR2: 2.5 15 R⊙) and two new designs
of heliospheric imagers (HI-1: 15 84 R⊙ and HI-2: 66 318
R⊙). All the instruments use 2048×2048 pixel CCD arrays
in a backside-in mode. The EUVI backside surface has been specially
processed for EUV sensitivity, while the others have an anti-reflection
coating applied. A multi-tasking operating system, running on a PowerPC
CPU, receives commands from the spacecraft, controls the instrument
operations, acquires the images and compresses them for downlink
through the main science channel (at compression factors typically
up to 20×) and also through a low bandwidth channel to be used for
space weather forecasting (at compression factors up to 200×). An
image compression factor of about 10× enable the collection of images
at the rate of about one every 2 3 minutes. Identical instruments,
except for different sizes of occulters, are included on the STEREO-A
and STEREO-B spacecraft.
Title: The SECCHI Experiment on the STEREO Mission
Authors: Howard, R. A.; Moses, J. D.; Vourlidas, A.; Newmark, J. S.;
Socker, D. G.; Wang, D.; Plunkett, S. P.; Baugh, R.; McMullin, D. R.;
Davila, J. M.; Thompson, W. T.; Lemen, J. R.; Wuelser, J.; Harrison,
R. A.; Waltham, N. R.; Davis, C. J.; Eyles, C. J.; Defise, J.; Halain,
J.; Bothmer, V.; Delaboudiniere, J.; Auchere, F.; Mercier, R.; Ravet,
M. F.
Bibcode: 2007AGUSMSH33A..01H
Altcode:
The Sun Earth Connection Coronal and Heliospheric Investigation
(SECCHI) on the NASA Solar Terrestrial Relations Observatory (STEREO)
mission is a suite of remote sensing instruments consisting of an
extreme ultraviolet (EUV) imager, two white light coronagraphs, and
two telescopes that comprise the heliospheric imager. SECCHI will
observe coronal mass ejections (CMEs) from their birth at the sun,
through the corona and into the heliosphere. A complete instrument
suite is being carried on each of the two STEREO spacecraft, which
will provide the first sampling of a CME from two vantage points. The
spacecraft, launched 25 October 2006, are orbiting the Sun, one Ahead
of the Earth and the other Behind, each separating from Earth at about
22 degrees per year. The varying separation means that we will have
different observational capabilities as the spacecraft separate and
therefore differing science goals. The primary science objectives
all are focused on understanding the physics of the CME process
their initiation, 3D morphology, propagation, interaction with the
interplanetary medium and space weather effects. By observing the CME
from multiple viewpoints with UV and coronagraphic telescopes and by
combining these observations with radio and in-situ observations from
the other instruments on STEREO as well as from other satellites and
ground based observatories operating at the same time, answers to some
of the outstanding questions will be obtained. We will show some of
the initial results.
Title: Stereo Observations Of The Solar Corona Using The Secchi
Experiment
Authors: Plunkett, Simon P.; Howard, R. A.; Moses, J. D.; Vourlidas,
A.; Socker, D.; Newmark, J.; Wang, D.; Baugh, R.; Davila, J.;
Thompson, W.; St. Cyr, O. C.; Lemen, J.; Wuelser, J. P.; Harrison,
R. A.; Waltham, N.; Davis, C. J.; Eyles, C. J.; Defise, J. M.; Halain,
J. P.; Bothmer, V.; Delaboudiniere, J. P.; Auchere, F.; Mercier, R.;
Ravet, M. F.
Bibcode: 2007AAS...21011901P
Altcode: 2007BAAS...39..243P
The Sun Earth Connection Coronal and Heliospheric Investigation
(SECCHI) on the NASA Solar Terrestrial Relations Observatory (STEREO)
mission is a suite of remote sensing instruments consisting of an
extreme ultraviolet (EUV) imager, two white light coronagraphs,
and two telescopes that comprise the heliospheric imager. The main
objective of SECCHI is to observe coronal mass ejections (CMEs) from
their birth at the sun, through the corona and into the heliosphere. A
complete instrument suite is being carried on each of the two STEREO
spacecraft, which will provide the first sampling of a CME from two
vantage points as the spacecraft separate from each other at the rate
of about 45 degrees per year. We will show examples of some of the
data and some of the initial stereo results.
Title: The SECCHI Experiment on the STEREO Mission
Authors: Howard, R. A.; Moses, D.; Vourlidas, A.; Newmark, J.; Socker,
D. G.; Plunkett, S.; Wang, D.; Baugh, R.; McMullin, D.; Davila, J.;
St. Cyr, C.; Thompson, W. T.; Lemen, J.; Wuelser, J.; Harrison, R. A.;
Waltham, N. R.; Davis, C.; Eyles, C. J.; Defise, J.; Halain, J.;
Bothmer, V.; Delaboudiniere, J.; Auchere, F.; Mercier, R.; Ravet, M.
Bibcode: 2006AGUFMSM12A..02H
Altcode:
The Sun Earth Connection Coronal and Heliospheric Investigation
(SECCHI) on the NASA Solar Terrestrial Relations Observatory (STEREO)
mission is a suite of remote sensing instruments consisting of an
extreme ultraviolet (EUV) imager, two white light coronagraphs, and
two telescopes that comprise the heliospheric imager. SECCHI will
observe coronal mass ejections (CMEs) from their birth at the sun,
through the corona and into the heliosphere. A complete instrument
suite is being carried on each of the two STEREO spacecraft, which
will provide the first sampling of a CME from two vantage points. The
spacecraft will orbit the Sun, one Ahead of the Earth and the other
Behind, each separating from Earth at about 22 degrees per year. The
varying separation means that we will have different observational
capabilities as the spacecraft separate and therefore differing science
goals. The primary science objectives all are focused on understanding
the physics of the CME process their initiation, 3D morphology,
propagation, interaction with the interplanetary medium and space
weather effects. By observing the CME from multiple viewpoints with UV
and coronagraphic telescopes and by combining these observations with
radio and in-situ observations from the other instruments on STEREO as
well as from other satellites and ground based observatories operating
at the same time, answers to some of the outstanding questions will
be obtained. STEREO follows the very successful SOHO mission. SOHO's
success was primarily due to the highly complementary nature of the
instruments, but it was partly due to the very stable platform. The
L1 orbit enables an extremely stable thermal environment and thus
very stable pointing, as well as uninterrupted solar viewing. The
STEREO will have both of these characteristics, but in addition will
have multi-viewpoint viewing of CMEs, which will greatly enhance the
many discoveries that SOHO data have produced. We have been developing
techniques to interpret the observations from multiple viewpoints and
to perform 3-dimensional deconvolution of the CME observations using
forward modeling and inversion techniques. A continuous downlink of
STEREO data will provide a low-resolution, real- time view from all
of the instruments. The full data are downlinked once a day and will
be available about 24 hours later. We will present some preliminary
results from the instrument, which is expected to be launched in
October/November, 2006
Title: A Spectroscopic Observation of a Magnetic Reconnection Site
in a Small Flaring Event
Authors: Hara, Hirohisa; Nishino, Yohei; Ichimoto, Kiyoshi;
Delaboudinière, Jean-Pierre
Bibcode: 2006ApJ...648..712H
Altcode:
We have observed two types of coronal bidirectional flows in a flare
with a small energy release through a spectroscopic observation of
the Fe X emission line at 6374 Å with a ground-based coronagraph
at the Norikura Solar Observatory. We find a bidirectional flow of
+/-3 km s-1 above the top of a flare loop. Remarkable
increases of the line intensity and line width are not observed in
the flow. From the loop geometry and sign of the Fe X Doppler velocity
we conclude that the bidirectional flow is reconnection inflow above
the flare loop. We estimate the reconnection rate to be ~0.003 for
this event. The other bidirectional flow is observed along postflare
loops with significant increases of the line intensity and Doppler
velocity. This flow is interpreted as a cooling upflow having a velocity
of ~10 km s-1 along a postflare loop from its lower part. We
also find that the increase of the nonthermal line width in the loop-top
region starts when the line intensity reaches its peak. This supports
the presence of a mechanism to enhance turbulent plasma motions in
the loop-top region.
Title: An atlas of solar events: 1996 2005
Authors: Artzner, G.; Auchère, F.; Delaboudinière, J. P.; Bougnet, M.
Bibcode: 2006AdSpR..38..390A
Altcode:
Coronal mass ejections (CMEs) are observed in the plane of the sky in
coronographic images. As the solar surface is masked by an occulting
disk it is not clear whether halo CMEs are directed towards or away
from the Earth. Observations of the solar corona on the solar disk
by the extreme ultraviolet imaging telescope (EIT) on board the Solar
Heliospheric Observatory SoHO can help to resolve this. Quasi-continuous
observations of the solar corona were obtained from April 1997 up to
the current date at a 12 min cadence in the coronal line of FeXII, as
part of a “CME watch program”. At a slower 6 h cadence an additional
synoptic program investigates the chromosphere and the corona at four
different wavelengths. Large coronal solar events appear when viewing
animations of the CME watch program. Fainter events do appear when
viewing running difference animations of the CME watch program. When
looking for additional spectral information from raw running differences
of the synoptic program it is difficult to disentangle intrinsic solar
events from the parasitic effect of the solar rotation. We constructed
at www.ias.u-psud.fr/medoc/EIT/movies/ an atlas of more than 40,000
difference images from the synoptic programme, corrected for an
average solar rotation, as well as more than 200,000 instantaneous and
difference images from the CME watch program. We present case studies
of specific events in order to investigate the source of darkenings or
dimmings in difference images, due to the removal of emitting material,
the presence of obscuring material or large changes in temperature. As
the beneficial effect of correcting for the solar rotation vanishes at
the solar limb, we do not investigate the case of prominence Doppler
dimming. As a by-product of the atlas of solar events we obtain a
number of quiet time sequences well suited to precisely measure the
differential solar rotation by the apparent displacement of tracers.
Title: Observations of Solar EUV Radiation with the CORONAS-F/SPIRIT
and SOHO/EIT Instruments
Authors: Slemzin, V. A.; Kuzin, S. V.; Zhitnik, I. A.; Delaboudiniere,
J. -P.; Auchere, F.; Zhukov, A. N.; van der Linden, R.; Bugaenko,
O. I.; Ignat'ev, A. P.; Mitrofanov, A. V.; Pertsov, A. A.; Oparin,
S. N.; Stepanov, A. I.; Afanas'ev, A. N.
Bibcode: 2005SoSyR..39..489S
Altcode:
The SPIRIT complex onboard the CORONAS-F satellite has routinely
imaged the Sun in the 171, 175, 195, 284, and 304 Å spectral bands
since August 2001. The complex incorporates two telescopes. The
Ritchey-Chretien telescope operates in the 171, 195, 284, and
304 Å bands and has an objective similar to that of the SOHO/EIT
instrument. The Herschel telescope obtains solar images synchronously
in the 175 and 304 Å bands with two multilayer-coated parabolic
mirrors. The SPIRIT program includes synoptic observations, studies of
the dynamics of various structures on the solar disk and in the corona
up to 5 solar radii, and coordinated observations with other spaceborne
and ground-based telescopes. In particular, in the period 2002-2003,
synoptic observations with the SPIRIT Ritchey-Chretien telescope were
coordinated with regular 6-hour SOHO/EIT observations. Since June 2003,
when EIT data were temporarily absent ( SOHO keyholes), the SPIRIT
telescope has performed synoptic observations at a wavelength of 175
A. These data were used by the Solar Influence Data Analysis Center
(SIDC) at the Royal Observatory of Belgium for an early space weather
forecast. We analyze the photometric and spectral parameters of the
SPIRIT and EIT instruments and compare the integrated (over the solar
disk) EUV fluxes using solar images obtained with these instruments
during the CORONAS-F flight from August 2001 through December 2003.
Title: Manifestations of Coronal Mass Ejections in the EUV Range
from Data of the CORONAS-F/SPIRIT Telescope
Authors: Chertok, I. M.; Grechnev, V. V.; Slemzin, V. A.; Kuzin,
S. V.; Bugaenko, O. I.; Zhitnik, I. A.; Ignat'ev, A. P.; Pertsov,
A. A.; Delaboudiniere, J. -P.
Bibcode: 2005SoSyR..39..462C
Altcode:
We briefly overview results of our study of the large-scale
solar activity associated with coronal mass ejections (CMEs). The
observational material is constituted with data of the SPIRIT telescope
aboard the CORONAS-F satellite in the three EUV channels 175, 284,
and 304 Å. In particular, we consider a powerful geoeffective event
of November 4, 2003, which was not observed by the SOHO/EIT telescope,
a series of extremely powerful events of October 2003, and an event
of November 18, 2003, with filament eruption. The efficiency of
combined analysis of the SPIRIT and EIT data is demonstrated. The
analysis confirms the coincidence of many dimmings in different
spectral channels, including coronal lines with different excitation
temperatures and the transition-region line, as well as the global
character and homology of dimmings in recurrent events. The higher
cadence SPIRIT observations at 304 Å reveal a slowly propagating
large-scale darkening probably caused by absorption of emission in
the dense, cold plasma of an eruptive filament.
Title: CORONAS-F/SPIRIT EUV observations of October-November 2003
solar eruptive events in combination with SOHO/EIT data
Authors: Grechnev, V. V.; Chertok, I. M.; Slemzin, V. A.; Kuzin, S. V.;
Ignat'ev, A. P.; Pertsov, A. A.; Zhitnik, I. A.; DelaboudinièRe,
J. -P.; AuchèRe, F.
Bibcode: 2005JGRA..110.9S07G
Altcode: 2005JGRA..11009S07G
The extraordinary solar activity of October-November 2003 manifested
itself in many powerful eruptive events, including large coronal mass
ejections (CMEs) and extremely powerful flares. A number of major
events were accompanied by practically all known phenomena of the solar
activity, both local and large-scale, and caused severe space weather
disturbances. We study large-scale posteruptive activity manifestations
on the Sun associated with CMEs, i.e., dimmings and coronal waves,
observed with extreme-ultraviolet telescopes, the SPIRIT on the
CORONAS-F spacecraft and the EIT on the SOHO. During that period,
observations with a cadence of 15 to 45 min were carried out by the
SPIRIT in the 175 Å and 304 Å bands simultaneously. The EIT observed
with 12-min cadence in the 195 Å band as well as with 6-hour cadence
in the 171, 284, and 304 Å bands. These data complement each other
both in the temporal and spectral coverage. Our analysis reveals
that largest-scale dimmings covered almost the whole southern part of
the Sun's visible side and exhibited homology, with one homological
structure being changed to another configuration on 28 October. These
structures show connections between large superactive and smaller
regions that constituted a huge activity complex responsible for the
extraordinary solar activity of that period. Coronal waves were observed
at 175 Å as well as at 195 Å in some events, in areas where there were
no active regions, but in the 175 Å images they look fainter. They
were not accompanied by deep, long-living dimmings. By contrast,
such dimmings were observed in active regions, in their vicinity,
and between them. These facts rule out the direct relation of the
phenomena of long-term dimmings and coronal waves. On 18 November, a
motion of an ejecta was observed at the solar disk as a propagation of
a dark feature only in the 304 Å band, which can be interpreted as an
absorption in a "cloud" formed from material of the eruptive filament,
which probably failed to become a CME core.
Title: Research on a complex CME event including Hα, LASCO, radio
and MDI observations
Authors: Wang, S. J.; Maia, D.; Pick, M.; Aulanier, G.; Malherbe,
J. -M.; Delaboudinière, J. -P.
Bibcode: 2005AdSpR..36.2273W
Altcode:
We present our research on a fast and decelerating partial halo
coronal mass ejection (CME) event detected in multi-wavelengths
in the chromosphere and the corona on 14 October, 1999. The event
involved a whole complex active area which spanned more than 40°
of heliolongitude. It included a strong solar flare (XI/1N) and a
complex eruptive filament within an active region of the entire
complex. Especially, several radio sources were detected in the
decimetric range prior to the CME by the Nançay Radioheliograph
(NRH). A linear force-free field extrapolation of the Michelson Doppler
Imager (MDI) magnetogram was performed to calculate the magnetic
topology of the complex prior to the triggering of the event. The
presence of a coronal null point combined with the occurrence of two
distant and nearly simultaneous radio sources put strong arguments
in favor of the generalized breakout model for the triggering of the
eruption. The analysis of the subsequent development of the event
suggests that large interconnecting loops were ejected together with
the CME.
Title: Shock Wave Driven by an Expanding System of Loops
Authors: Raouafi, N. -E.; Mancuso, S.; Solanki, S. K.; Inhester, B.;
Mierla, M.; Stenborg, G.; Delaboudinière, J. P.; Benna, C.
Bibcode: 2005IAUS..226..127R
Altcode:
We report on a Coronal Mass Ejection (CME) observed on June 27
1999 by the UltraViolet Coronagraph Spectrometer (UVCS) telescope
operating on board the SOHO spacecraft. The CME was also observed
by LASCO (SOHO). Emission of hot material has been recorded by UVCS
propagating in front of an opening system of loops generated by the
CME. The evolution of the UVCS structure is highly correlated to the
evolution of the opening loop. The data reveal excess broadening of
the O VI doublet lines and an enhancement in the intensity of the Si
XII λ 520.66 and λ499.37 lines due to the motion of the expanding hot
gas. The hot gas emission seems to be due to a shock wave propagating in
front of a very fast gas bubble traveling along the opening loop system.
Title: HERSCHEL Suborbital Program: 3-D Applications for the STEREO
Mission
Authors: Moses, J. D.; Newmark, J.; McMullin, D.; Antonucci, E.;
Fineschi, S.; Gardiol, D.; Zangrilli, L.; Romoli, M.; Pace, E.; Gori,
L.; Landini, F.; Gherardi, A.; da Deppo, V.; Naletto, G.; Nicolosi, P.;
Pelizzo, M.; Malvezzi, M.; Auchere, F.; Delaboudiniere, J.; Howard, R.
Bibcode: 2004AGUFMSH23A..08M
Altcode:
The HERSCHEL (HElium Resonance Scatter in the Corona and HELiosphere)
Suborbital Program is an international collaborative program between
a consortium of Italian Universities & Observatories led by
Dr. E. Antonucci (and funded by the Italian Space Agency, ASI), the
French IAS (funded in part by CNES) and the Solar Physics Branch of
NRL (by NASA SEC and the Office of Naval Research). HERSCHEL will:
investigate the slow and fast solar wind, determine the helium
distribution and abundance in the corona, and test solar wind
acceleration models; by obtaining simultaneous observations of
the electron, proton and helium solar coronae. HERSCHEL will also
establish proof-of-principle for the Ultra-Violet Coronagraph, which
is in the ESA Solar Orbiter Mission baseline. The HERSCHEL launch date
has been linked to the STEREO launch date to allow coordinated science
between the two missions. One aspect of this scientific coordination is
establishing the 3-D structure of the inner corona. HERSCHEL provides
a third viewpoint for the inner corona covered by the A&B STEREO
SECCHI COR-1. HERSCHEL is the only scheduled, space-based asset that
could provide this third viewpoint for the critical inner corona viewed
by STEREO COR-1 (although lower resolution, ground-based cononagraphs
will make a contribution). A third viewpoint dramatically increases
one's ability to establish the 3-D structure of an optically thin object
(e.g. the metric in Fig. 7 of Davila 1994, ApJ 423, 871). HERSCHEL will
provide at least a snapshot of that viewpoint, plus a wide range of
additional information on the H and He composition of the inner corona.
Title: Shock wave driven by an expanding system of loops
Authors: Raouafi, N. -E.; Mancuso, S.; Solanki, S. K.; Inhester, B.;
Mierla, M.; Stenborg, G.; Delaboudinière, J. P.; Benna, C.
Bibcode: 2004A&A...424.1039R
Altcode:
We report on a Coronal Mass Ejection (CME) observed on June 27, 1999 by
the UltraViolet Coronagraph Spectrometer (UVCS) telescope operating on
board the SOHO spacecraft. The CME was also observed by the Large Angle
Spectroscopic Coronagraph (LASCO). Emission of hot material has been
recorded by UVCS propagating in front of an opening system of loops
generated by the CME. The evolution of the UVCS structure is highly
correlated with the evolution of the opening loop. The data reveal
excess broadening of the O VI doublet lines and an enhancement in the
intensity of the Si XII λ520.66 and λ499.37 lines due to the motion
of the expanding hot gas. The hot gas emission seems to be due to a
shock wave propagating in front of a very fast gas bubble traveling
along the opening loop system.
Title: The August 11th, 1999 CME
Authors: Koutchmy, S.; Baudin, F.; Bocchialini, K.; Daniel, J. -Y.;
Delaboudinière, J. -P.; Golub, L.; Lamy, P.; Adjabshirizadeh, A.
Bibcode: 2004A&A...420..709K
Altcode:
We present here a set of observations, space borne and ground based,
at different wavelengths, of the solar corona at and after the time of
the total solar eclipse of August 11{th}. It is used to consider some
unusual features of the coronal dynamics related to a limb Coronal Mass
Ejection (CME) observed after the total eclipse. The complementary
aspect of simultaneous ground-based and space-borne observations
of the corona is used to produce an accurate composite image of the
White Light (W-L) corona before the CME. A high arch system (possibly
a dome-like structure, with large cavities inside but without a cusp
further out) which appeared on the eclipse W-L images, is suggested to
be a large-scale precursor of the CME, well preceding the eruption of
the top part of the brightest prominence recorded in W-L. This bright
prominence is shown as a filament in absorption using the Transition
Region And Corona Explorer (TRACE) images taken in different coronal
lines. The analysis of the images of the Large Angle and Spectrometric
Coronograph (LASCO) on board the Solar and Heliospheric Observatory
(SoHO), showing the progression of the CME, is discussed in an attempt
to make a connection with the surface event. A SoHO-EIT (Extreme
UV Imager Telescope) image sequence details the prominence eruption
and shows the sudden heating processes of the ejected parts. We found
that there is no reason to assume that the huge cavity is significantly
destabilised well before the eruption of the upper part of the low-lying
bright twisted filament which coincides with the position of one of
the legs of the high arch. Observations are still compatible with the
assumption of both the break-out model and of the flux rope erupting
model as a result of a shear or of an increasing poloıdal magnetic
flux from below. We stress the possible role of buoyancy of the giant
cavity as a destabilizing factor leading to the CME, noticing that some
motion of coronal material back toward the surface can be seen during at
least the first phase of the CME, from both EIT and LASCO observations.
Title: Ion beam deposited Mo/Si multilayers for EUV imaging
applications in astrophysics
Authors: Ravet, Marie-Francoise; Bridou, Francoise; Zhang-Song, Xueyan;
Jerome, Arnaud; Delmotte, Franck; Mercier, Raymond; Bougnet, Marie;
Bouyries, Philippe; Delaboudiniere, Jean-Pierre
Bibcode: 2004SPIE.5250...99R
Altcode:
Imaging of the solar corona by selecting Fe IX (λ=17.1nm,), Fe XII
(λ=19.5nm), Fe XV (λ=28.4nm) and He II (λ=30.4nm) emission lines
with a Ritchey-Chretien telescope requires to coat the optics with
multilayers having a high accuracy in their layer thicknesses, a
high reflectivity and an optimal bandpass. Multilayers were simulated
in order to determine the most adequate formula for each wavelength
channel. Mo/Si coatings were deposited by using the ion beam sputtering
technique in a high vacuum chamber equipped with a micro balance and
an in-situ reflectometer. The multilayers were studied by grazing angle
reflectometry at 0.1541nm, and their reflectances around the operating
wavelengths were measured on the SA62 IAS/LURE beam line of the SuperACO
synchrotron facility located at Orsay. In addition, aging versus time
and behavior of the multilayers under a rapid thermal annealing were
investigated. Performances of the ion-beam deposited multilayers have
been improved compared to the Mo/Si coatings obtained in the past
by the e-beam evaporation technique for the SOHO mission Extreme UV
Imaging Telescope (EIT). The EUVI telescopes for the STEREO mission
are being proceduced by depositing these new generation of multilayers
onto primary and secondary mirrors. The reflectivity measurements on
a telescope are presented.
Title: MAGRITTE: an instrument suite for the solar atmospheric
imaging assembly (AIA) aboard the Solar Dynamics Observatory
Authors: Rochus, Pierre L.; Defise, Jean-Marc; Halain, Jean-Philippe;
Jamar, Claude A. J.; Mazy, Emmanuel; Rossi, Laurence; Thibert,
Tanguy; Clette, Frederic; Cugnon, Pierre; Berghmans, David; Hochedez,
Jean-Francois E.; Delaboudiniere, Jean-Pierre; Auchere, Frederic;
Mercier, Raymond; Ravet, Marie-Francoise; Delmotte, Franck; Idir,
Mourad; Schuehle, Udo H.; Bothmer, Volker; Fineschi, Silvano; Howard,
Russell A.; Moses, John D.; Newmark, Jeffrey S.
Bibcode: 2004SPIE.5171...53R
Altcode:
The Solar Atmospheric Imaging Assembly (AIA) aboard the Solar Dynamics
Observatory will characterize the dynamical evolution of the solar
plasma from the chromosphere to the corona, and will follow the
connection of plasma dynamics with magnetic activity throughout the
solar atmosphere. The AIA consists of 7 high-resolution imaging
telescopes in the following spectral bandpasses: 1215Å. Ly-a,
304 Å He II, 629 Å OV, 465 Å Ne VII, 195 Å Fe XII (includes Fe
XXIV), 284 Å Fe XV, and 335 Å Fe XVI. The telescopes are grouped
by instrumental approach: the MAGRITTE Filtergraphs (R. MAGRITTE,
famous 20th Century Belgian Surrealistic Artist), five multilayer EUV
channels with bandpasses ranging from 195 to 1216 Å, and the SPECTRE
Spectroheliograph with one soft-EUV channel at OV 629 Å. They will be
simultaneously operated with a 10-second imaging cadence. These two
instruments, the electronic boxes and two redundant Guide Telescopes
(GT) constitute the AIA suite. They will be mounted and coaligned on a
dedicated common optical bench. The GTs will provide pointing jitter
information to the whole SHARPP assembly. This paper presents the
selected technologies, the different challenges, the trade-offs to be
made in phase A, and the model philosophy. From a scientific viewpoint,
the unique combination high temporal and spatial resolutions with the
simultaneous multi-channel capability will allow MAGRITTE / SPECTRE
to explore new domains in the dynamics of the solar atmosphere, in
particular the fast small-scale phenomena. We show how the spectral
channels of the different instruments were derived to fulfill the
AIA scientific objectives, and we outline how this imager array will
address key science issues, like the transition region and coronal waves
or flare precursors, in coordination with other SDO experiments. We
finally describe the real-time solar monitoring products that will be
made available for space-weather forecasting applications.
Title: EUVI: the STEREO-SECCHI extreme ultraviolet imager
Authors: Wuelser, Jean-Pierre; Lemen, James R.; Tarbell, Theodore
D.; Wolfson, C. J.; Cannon, Joseph C.; Carpenter, Brock A.; Duncan,
Dexter W.; Gradwohl, Glenn S.; Meyer, Syndie B.; Moore, Augustus S.;
Navarro, Rosemarie L.; Pearson, J. D.; Rossi, George R.; Springer,
Larry A.; Howard, Russell A.; Moses, John D.; Newmark, Jeffrey S.;
Delaboudiniere, Jean-Pierre; Artzner, Guy E.; Auchere, Frederic;
Bougnet, Marie; Bouyries, Philippe; Bridou, Francoise; Clotaire,
Jean-Yves; Colas, Gerard; Delmotte, Franck; Jerome, Arnaud; Lamare,
Michel; Mercier, Raymond; Mullot, Michel; Ravet, Marie-Francoise;
Song, Xueyan; Bothmer, Volker; Deutsch, Werner
Bibcode: 2004SPIE.5171..111W
Altcode:
The Extreme Ultraviolet Imager (EUVI) is part of the SECCHI instrument
suite currently being developed for the NASA STEREO mission. Identical
EUVI telescopes on the two STEREO spacecraft will study the structure
and evolution of the solar corona in three dimensions, and specifically
focus on the initiation and early evolution of coronal mass ejections
(CMEs). The EUVI telescope is being developed at the Lockheed Martin
Solar and Astrophysics Lab. The SECCHI investigation is led by the
Naval Research Lab. The EUVI"s 2048 x 2048 pixel detectors have a
field of view out to 1.7 solar radii, and observe in four spectral
channels that span the 0.1 to 20 MK temperature range. In addition to
its view from two vantage points, the EUVI will provide a substantial
improvement in image resolution and image cadence over its predecessor
SOHO-EIT, while complying with the more restricted mass, power, and
volume allocations on the STEREO mission.
Title: Dynamics of the loop prominence and coronal mass ejection
observed on March 2, 2002
Authors: Panasenco, O.; Veselovsky, I. S.; Zhukov, A. N.; Yakovchouk,
O. S.; Koutchmy, S.; Delaboudiniere, J. -P.
Bibcode: 2004cosp...35.2974P
Altcode: 2004cosp.meet.2974P
SOHO/EIT and LASCO data are used for the case study of the coronal mass
ejection initiation and development. The shape, velocity and temperature
of the loop prominence before and during the ejection as well as the
new arcade formation are well documented. The prominence consisted of
two spirals interweaved on the semi-torus. Both spirals are clearly
seen during the initial stage of the expansion with a velocity about
300 km/s. Than, one of them is rapidly heated, when other remained
cool. The number of curls is conserved during the expansion. The
main axis of the torus is initially represented by the planar curve
resembling a semi-circle. After some time, the summit of the torus
is twisted in the manner that the main axis looks not planar at the
top in the field of view of LASCO C3 when the velocity attains about
1000 km/s. The topological connectivity of the loops to the Sun is
preserved for more than three hours even after the new arcade formation.
Title: An atlas of solar events: 1997-2004
Authors: Artzner, G.; Auchère, F.; Delaboudinière, J. P.; Bougnet, M.
Bibcode: 2004cosp...35.2494A
Altcode: 2004cosp.meet.2494A
Coronal mass ejections (CMEs) are observed in the plane of the sky
from coronographic images. As the solar surface is then masked by an
occulting disk, it is not clear wether halo CMEs are directed towards
the Earth or in the opposite direction. Observations of the solar corona
on the solar disk from the Extreme Ultraviolet Imaging Telescope EIT on
board the Solar Heliospheric Observatory SoHO do help in order to make
a choice. Quasi-continuous observations of the corona of the Sun have
been therefore obtained from april 1997 up to now at a twelve minute
cadence in the coronal line of FeXII, as a CME watch program. At a
slower six hours cadence an additional synoptic program investigates
the chromosphere and the corona at four different wavelengths. Large
coronal solar events appear when viewing animations of the CME watch
program. Fainter events do appear when viewing running difference
animations of the CME watch program. When looking for additional
spectral information from raw running differences of the synoptic
program it is difficult to disentangle intrinsic solar events from
the parasitic effect of the solar rotation. We constructed from the
synoptic program observations an atlas of more than 20 000 difference
images corrected for an average solar rotation. We present case studies
of specific events in order to investigate the source of darkenings in
difference images, either removal of emitting material, interposition
of obscuring material or large changes of temperature. Statistics
of brigtenings and darkenings along solar cycle 23 are presented. We
speculate about future observations from the STEREO mission in order
to obtain better diagnostics about darkenings. As a by product of the
atlas of solar events we obtain a number of quiet time sequences well
suited in order to precisely measure the differnetial solar rotation
by the apparent displacement of tracers.
Title: Multi-wavelength observations of CME-associated structures
on the Sun with the CORONAS-F/SPIRIT EUV telescope
Authors: Slemzin, V.; Chertok, I.; Grechnev, V.; Ignat'ev, A.; Kuzin,
S.; Pertsov, A.; Zhitnik, I.; Delaboudinière, J. -P.
Bibcode: 2004IAUS..223..533S
Altcode: 2005IAUS..223..533S
Multi-wavelength imaging of the solar corona is a powerful observational
method to study CME-related dynamics of structures in spectral
bands related to the solar corona and transition region. We analyze
large-scale eruptive events caused by halo-type CMEs observed at the
solar disk with the CORONAS-F/SPIRIT (175, 304, and 284 Å) and SOHO/EIT
telescopes on November 4, 2001 and October-November, 2003. For most
events, CME-associated dimmings coincide in different bands, but the 304
Å dimming in November 4, 2001 event was delayed by >1/2 hours. In
October-November events, coronal waves were observed in 195 Å and some
in 175 Å channel. In a CME event associated with a filament eruption
on November 18, the SPIRIT images display a propagating disturbance
seen as a darkening in 304 Å channel only. This phenomenon was not
described earlier.
Title: Interpretation of the Coronal EUV Signature of the CME Event
on June 27 1999
Authors: Raouafi, N. -E.; Mancuso, S.; Solanki, S. K.; Inhester, B.;
Benna, C.; Delaboudinière, J. P.; Stenborg, G.; Mierla, M.
Bibcode: 2004ESASP.547..317R
Altcode: 2004soho...13..317R
We report the observation of a Coronal Mass Ejection (CME) detected
on June 27 1999 by the UltraViolet Coronagraph Spectrometer (UVCS)
telescope operating on board the SOHO spacecraft. The CME, whose
leading edge was expanding at a projected speed of about 1200 km s,
was observed in white light by the Large Angle Spectroscopic Coronagraph
(LASCO). The UVCS spectra reveal excess broadening of the O VI doublet
lines and enhancement in the intensity of the Si XII lines due to the
motion of expanding hot material. The evolution of the UVCS structure
is highly correlated to the evolution of the CME observed by LASCO
in white light, so that the hot gas emission could be attributable to
the passage of a shock wave propagating just in front of the fast CME.
Title: The Ultraviolet and Visible-light Coronagraph of the HERSCHEL
experiment
Authors: Romoli, M.; Antonucci, E.; Fineschi, S.; Gardiol, D.;
Zangrilli, L.; Malvezzi, M. A.; Pace, E.; Gori, L.; Landini, F.;
Gherardi, A.; da Deppo, V.; Naletto, G.; Nicolosi, P.; Pelizzo, M. G.;
Moses, J. D.; Newmark, J.; Howard, R.; Auchere, F.; Delaboudinière,
J. P.
Bibcode: 2003AIPC..679..846R
Altcode:
The Herschel (HElium Resonant Scattering in the Corona and HELiosphere)
experiment, to be flown on a sounding rocket, will investigate the
helium coronal abundance and the solar wind acceleration from a
range of solar source structures by obtaining the first simultaneous
observations of the electron, proton and helium solar corona. The
HERSCHEL payload consists of the EUV Imaging Telescope (EIT), that
resembles the SOHO/EIT instrument, and the Ultraviolet and Visible
Coronagraph (UVC).UVC is an imaging coronagraph that will image
the solar corona from 1.4 to 4 solar radii in the EUV lines of HI
121.6 nm and the HeII 30.4 nm and in the visible broadband polarized
brightness. The UVC coronagraph is externally occulted with a novel
design as far as the stray light rejection is concerned. Therefore,
HERSCHEL will also establish proof-of-principle for the Ultraviolet
Coronagraph, which is in the ESA Solar Orbiter Mission baseline.The
scientific objectives of the experiment will be discussed, togetherwith
a description of the UVC coronagraph.
Title: Interpretation of a complex CME event: Coupling of scales in
multiple flux systems
Authors: Maia, D.; Aulanier, G.; Wang, S. J.; Pick, M.; Malherbe,
J. -M.; Delaboudinière, J. -P.
Bibcode: 2003A&A...405..313M
Altcode:
Using multi-wavelength observations, in particular in imagery, recorded
by SOHO/LASCO-MDI, Yohkoh/SXT, the Meudon spectroheliograph and the
Nançay radioheliograph, and performing a linear force-free field
extrapolation, we analyzed the triggering and the development of a
complex eruptive event in the chromosphere and in the corona. This
event included an X1 class flare and an eruptive filament within an
active region, but it also involved a whole active complex spanning over
40 degrees of heliolongitude. It resulted in a fast and decelerating
partial halo CME, associated with a Moreton wave and a complex series
of metric, decimetric and microwave radio bursts. The presence of a
coronal null point combined with the occurrence of two distant and
nearly simultaneous radio sources give strong arguments in favor of
the generalized breakout model for the triggering of the eruption. The
observations are consistent with the occurrence of magnetic reconnection
at the null point three minutes before the start of the eruption,
which is consistent with other observed CME precursors. The analysis
of the subsequent development of the event suggests that large
interconnecting loops were ejected together with the CME, and that
secondary reconnections at low altitude probably occurred remotely in
the active complex. Our results show that the triggering and evolution
of this complex CME involved multiple magnetic flux systems over a
large coronal volume surrounding the flare site, and that it resulted
from the coupling of scales from narrow reconnection current sheets
to very large inter active region magnetic connections.
Title: The solar high-resolution imager - coronagraph LYOT mission
Authors: Vial, Jean-Claude; Song, Xueyan; Lemaire, Philippe; Gabriel,
Alan H.; Delaboudiniere, Jean-Pierre; Bocchialini, Karine; Koutchmy,
Serge L.; Lamy, Philippe L.; Mercier, Raymond; Ravet, Marie Francoise;
Auchere, Frederic
Bibcode: 2003SPIE.4853..479V
Altcode:
The LYOT (LYman Orbiting Telescope) solar mission is proposed to
be implemented on a micro-satellite of CNES (France) under phase A
study. It includes two main instruments, which image the solar disk
and the low corona up to 2.5 Ro in the H I Lyman-α line
at 121.6 nm. The spatial resolution is about 1” for the disk and
2.5” for corona. It also carries an EIT-type telescope in the He II
(30.4 nm) line. The coronagraph needs a super polished mirror at the
entrance pupil to minimize the light scattering. Gratings and optical
filters are used to select the Lyman-α wavelength. VUV cameras with
2048×2048 pixels record solar images up to every 10 seconds. The
satellite operates at a high telemetry rate (more then 100 kb/s,
after onboard data compression). The envisaged orbits are either
geostationary or heliosynchronous. Possible launch dates could be end
of 2006 - beginning of 2007.
Title: Photon sieves as EUV telescopes for Solar Orbiter
Authors: Artzner, Guy E.; Delaboudiniere, Jean Pierre; Song, Xueyan
Bibcode: 2003SPIE.4853..158A
Altcode:
We elaborate about obtaining images of the solar disc and of the solar
corona at discrete wavelengths along the EUV emission solar spectrum
on board the Solar Orbiter spacecraft. Refractive optics cannot be
used. The thermal load is twenty five times higher than on a near Earth
orbit. As on one side the efficiency of a stenopeic device is too low,
and as on the other side mirrors exposed directly to the light and
to the particles emitted by the Sun may severely degrade during time,
we investigated using the EUV analog of a Fresnel lens, i.e. a photon
sieve. An opaque self supporting flat piece of heat resistant metal
let the solar light shine through a large numbers of a few thousand
holes properly designed in positions and diameters in order to obtain
constructive interferences at some focus. We report about practical
experiments in the visible.
Title: Grazing incidence objective grating spectro-imagers for EUV
observations of the solar corona
Authors: Delaboudiniere, Jean-Pierre; Zhitnik, Igor A.; Ravet,
Marie-Francoise; Lepere, Didier
Bibcode: 2003SPIE.4853..393D
Altcode:
Objective grating spectrometers have been used previously to image the
sun in the EUV proving simultaneous images at several wavelengths. The
grazing incidence variant of this type of instrument seems well adapted
for application to the future ‘Solar Orbiter’ mission planned by
the ESA where thermal problems are expected to be severe. This type
of optical arrangements also provide more flexibility for the optimal
selection of performances.
Title: MAGRITTE / SPECTRE : the Solar Atmospheric Imaging Assembly
(AIA) aboard the Solar Dynamics Observatory
Authors: Rochus, P.; Defise, J. M.; Halain, J. P.; Mazy, E.; Jamar, C.;
Clette, F.; Cugnon, P.; Berghmans, D.; Hochedez, J. F.; Delaboudiniere,
J. P.; Artzner, G.; Auchere, F.; Mercier, R.; Ravet, M. F.; Delmotte,
M.; Idir, M.; Fineschi, S.; Antonucci, E.; Harrison, R. A.; Howard,
R. A.; Moses, J. D.; Newmark, J. S.
Bibcode: 2002AGUFMSH21C..05R
Altcode:
The Solar Atmospheric Imaging Assembly (AIA) aboard the Solar
Dynamics Observatory will characterize the dynamical evolution of
the solar plasma from the chromosphere to the corona, and will follow
the connection of plasma dynamics with magnetic activity throughout
the solar atmosphere. The AIA consists of 7 high resolution imaging
telescopes in the following spectral bandpasses: 1215 \x8F Ly-a, 304
\x8F He II, 629 \x8F OV, 465 \x8F Ne VII, 195 \x8F Fe XII (includes Fe
XXIV), 284 \x8F Fe XV, and 335 \x8F Fe XVI. The telescopes are grouped
by instrumental approach: the Magritte Filtergraphs (R. Magritte,
famous 20th Century Belgian Surrealistic Artist), five multilayer EUV
channels with bandpasses ranging from 195 to 1216 \x8F, and the SPECTRE
Spectroheliograph with one soft-EUV channel at OV 629 \x8F. They will
be simultaneously operated with a 10-second imaging cadence. These two
instruments, the electronic boxes and two redundant Guide Telescopes
(GT) constitute the AIA suite. They will be mounted and coaligned on a
dedicated common optical bench. The GTs will provide pointing jitter
information to the whole SHARPP assembly. This poster presents the
selected technologies, the different challenges, the trade-offs to be
made in phase A, and the model philosophy. From a scientific viewpoint,
the unique combination high temporal and spatial resolutions with the
simultaneous multi-channel capability will allow Magritte/SPECTRE
to explore new domains in the dynamics of the solar atmosphere, in
particular the fast small-scale phenomena. We show how the spectral
channels of the different instruments were derived to fulfill the
AIA scientific objectives, and we outline how this imager array will
address key science issues, like the transition region and coronal waves
or flare precursors, in coordination with other SDO experiments. We
finally describe the real-time solar monitoring products that will be
made available for space-weather forecasting applications.
Title: SPIRIT X-ray telescope/spectroheliometer results
Authors: Zhitnik, I. A.; Bougaenko, O. I.; Delaboudiniere, J. -P.;
Ignatiev, A. P.; Korneev, V. V.; Krutov, V. V.; Kuzin, S. V.; Lisin,
D. V.; Mitrofanov, A. V.; Oparin, S. N.; Oraevsky, V. N.; Pertsov,
A. A.; Slemzin, V. A.; Sobelman, I. I.; Stepanov, A. I.; Schwarz, J.
Bibcode: 2002ESASP.506..915Z
Altcode: 2002ESPM...10..915Z; 2002svco.conf..915Z
The SPIRIT X-ray telescope/spectroheliometer successively operates
on-board the Coronas-F satellite since August 15, 2001. The
instrument includes two XUV-solar telesocpes - one is a four-band
Ritchey-Chretien telescope (171, 195, 284 and 304 Å) with the optics
analogous to the EIT SOHO telesocpe, another - a Herschel two-band
(175 and 304 Å) telescope with off-axis paraboloids. The last one can
operate as an XUV-coronagraph with "artificial moons" in the field
up to 3 RSun. The spectroheliometer includes two Mg XII
(8.42 Å) full-Sun imaging spectrometers, two XUV spectroheliometers
with objective grazing incidence diffraction gratings, each has two
selectable spectral bands 177-207 and 285-335 Å, and Bragg crystal
Fe XXV (1.85-1.87 Å) imaging spectroheliometer. During the first year
there were observed flares and highly variable active structures in hot
10 MK Mg XII images, solar XUV-corona, full-Sun XUV spectral images,
solar XUV-corona, full-Sun XUV spectral images, first separated images
of solar disk and corona in the He II and Si XI lines (303.78 and
303.32 Å).
Title: Multi wavelength investigation of the eruption of a sigmoidal
quiescent filament
Authors: Marqué, Ch.; Lantos, P.; Delaboudinière, J. P.
Bibcode: 2002A&A...387..317M
Altcode:
We report the first observation of a filament eruption in the metric and
decimetric range, where the behavior of the filament can be followed
during the event via thermal radio emission diagnostics. The event,
occurring on February 28th 2001, involved a quiescent filament in a
sigmoid magnetic configuration, whose eruption is triggered by the
birth of a small parasitic polarity. Faint radio bursts mark the
beginning of the event, which shows the appearance of a brightness
temperature depression associated with the filament seen in F0B, and
its propagation on the disk up to the limb. The event is associated
with a halo CME observed with the coronagraphs LASCO C2 and C3, which
shows a significant spatial and temporal continuity with the radio
observations. Finally, static dimmings, similar to what is currently
observed in EUV or SXR domains, are also detected in the radio band,
around the site of the eruption. Movies of the event are attached
to this article. The movies are available in electronic form at
http://www.edpsciences.org
Title: The August 11th, 1999 total eclipse CME
Authors: Koutchmy, S.; Baudin, F.; Bocchialini, K.; Delaboudinière,
J. -P.; Adjabshirizadeh, A.
Bibcode: 2002ESASP.477...55K
Altcode: 2002scsw.conf...55K
We use spaceborne observations and ground-based eclipse observations
to analyse the spectacular W-limb CME which occurred several hours
after the totality in Iran. The underlying high arch system (possibly
a dome-like structure with cavities inside) which appeared on the
eclipse White-Light (W-L) images, is suggested to be a large scale
precursor of the CME, taking into account the related coronal cavities
(as measured from the broadening of the green Fe XIV line) and the
properties of the inserted prominence which erupted during the CME.
Title: Coronal Restructuring and Particle Acceleration During
Relativistic Solar Proton Events
Authors: Klein, K. -L.; Trottet, G.; Delaboudinière, J. P.
Bibcode: 2002EGSGA..27.3049K
Altcode:
The early temporal evolution of four relativistic proton events of the
current solar cy- cle is compared with broadband radio observations of
nonthermal electrons and with images of coronal plasma structures (EIT,
LASCO on SoHO). The events are accom- panied by fast and extended CMEs
and flares. The data contradict the widely cited idea that flares -
i.e. small-scale energy release in magnetically stressed structures of
the corona - are irrelevant to the production of energetic particles
detected at 1 AU during large "gradual" particle events: We show that
radio sources at dm-m- (Nançay Radio Heliograph) cover angular ranges
comparable to the CMEs. Even in cases where the flaring active region
is poorly connected, a radio source is found close to the nominal
Earth-connected interplanetary field line. The electron acceleration
revealed by these sources lasts longer than the soft X-ray event. The
accelerated electrons may attain mildly relativistic energies. The
acceleration process is probably related with the re- structuring of
the corona in the aftermath of the CME, at heights between 0.1 and 1
solar radius above the photosphere, but clearly not with the front of
the CME and its presumed shock wave. Since the solar release of
the relativistic protons is delayed with respect to the flare onset
during these events, but occurs during the long lasting radio emission,
we argue that the coronal sites of electron acceleration are plausible
sources of the relativistic protons detected at 1 AU, too.
Title: The Radiometric Calibration of the Extreme Ultraviolet
Imaging Telescope
Authors: Clette, F.; Hochedez, J. -F.; Newmark, J. S.; Moses, J. D.;
Auchère, F.; Defise, J. -M.; Delaboudinière, J. -P.
Bibcode: 2002ISSIR...2..121C
Altcode: 2002ESASR...2..121C; 2002rcs..conf..121C
After a five-year effort, the analysis of the pre-flight and in-flight
calibrations of EIT is finally yielding firm results. In this
introductory overview, we will summarize what we learned "internally"
from EIT itself. This includes the interpretation of the pre-flight
calibrations, the original flat-field components (CCD, grid), the
in-flight determination of the point-spread function and straylight and
the compensation of the in-orbit response degradation. Based on this
experience, we conclude with some suggestions of possible improvements
to future calibrations, on SOHO and other planned missions.
Title: Measurement of coronal magnetic twists during loop emergence
of NOAA 8069
Authors: Portier-Fozzani, F.; Aschwanden, M.; Démoulin, P.; Neupert,
W.; EIT Team; Delaboudinière, J. -P.
Bibcode: 2001SoPh..203..289P
Altcode:
Emerging coronal loops were studied with extreme ultraviolet
observations performed by SOHO/EIT on 5 and 6 August 1997 for NOAA
8069. Physical parameters (size and twist) were determined by a new
stereoscopic method. The flux tubes were measured twisted when first
observed by EIT. After emerging, they de-twisted as they expanded,
which corresponds to a minimization of the energy. Different scenarios
which take into account the conservation of the magnetic helicity are
discussed in relation with structure and temperature variations.
Title: Erratum: Coronal electron acceleration and relativistic proton
production during the 14 July 2000 flare and CME
Authors: Klein, K. -L.; Trottet, G.; Lantos, P.; Delaboudinière,
J. -P.
Bibcode: 2001A&A...377..687K
Altcode:
No abstract at ADS
Title: Coronal electron acceleration and relativistic proton
production during the 14 July 2000 flare and CME
Authors: Klein, K. -L.; Trottet, G.; Lantos, P.; Delaboudinière,
J. -P.
Bibcode: 2001A&A...373.1073K
Altcode:
The large solar flare of 14 July 2000 10 UT occurred in an active
region near the central meridian. It was accompanied by the eruption
of a filament and a rapid halo-type coronal mass ejection (CME). Large
particle fluxes were detected up to relativistic energies at 1 AU. In
this paper accelerated particles and plasma structures in the corona
are traced using radio, X-ray, EUV and visible light observations,
together with neutron monitor measurements of relativistic protons
at 1 AU. Both the bulk of the radio emission at decimetric and longer
waves and the escape of suprathermal electrons and relativistic protons
from the Sun were delayed by 10-20 min with respect to the hard X-ray
emission. Despite the delay and the association with a flare near the
central meridian the neutron monitor time profile was impulsive. We show
that the escape of the relativistic protons occurred in time coincident
both with a coronal shock wave, which may be the bow shock of the CME,
and with radio sources which trace electron acceleration and magnetic
field reconfiguration in the western hemisphere. Three observations
support the idea that the relativistic protons were accelerated
during this reconfiguration, at heights between 0.1 and 1 R_sun above
the photosphere, and not in the flaring active region or at the bow
shock of the CME: (i) the rise of the neutron monitor count rates is
simultaneous with the brightening of a new continuum radio source;
(ii) the duration of the continuum emission is similar to the rise
time of the neutron monitor count rates; (iii) the radio source is
close to the Earth-connected interplanetary magnetic field line.
Title: Calibration and flight of the NRL EIT CalRoc
Authors: Newmark, Jeffrey S.; Moses, J. Daniel; Cook, John W.;
Delaboudiniere, Jean-Pierre; Song, Xueyan; Carabetian, Charles;
Bougnet, Marie; Brunaud, Jacqueline; Defise, Jean-Marc; Clette,
Frederic; Hochedez, Jean-Francois E.
Bibcode: 2000SPIE.4139..328N
Altcode:
The ability to derive physical parameters of the Sun from observations
by the Solar and Heliospheric Observatory (SOHO) Extreme Ultraviolet
Imaging Telescope (EIT) greatly increases the scientific return of the
mission. The absolute and time variable calibration of EIT therefore is
of extreme interest. The NRL EIT Calibration Sounding Rocket (CalRoc)
program was initiated to provide well calibrated, contemporaneous
observations in support of SOHO EIT. These observations provide
three benefits to the SOHO EIT data, absolute calibration points,
temporal and spatial information of the EIT EUV response variability
in flight via flat field information and clues to the physics of the
degradation. Details of the bandpasses of the multilayered optics and
the total telescope photometry are presented. Comparisons are shown
with the contemporaneous images from SOHO EIT. Plans for the second
CalRoc flight are discussed. Loss of reflectivity in the multilayer
mirrors has been identified as a new component to the SOHO EIT and
CalRoc degradation.
Title: The Preflight Photometric Calibration of the
Extreme-Ultraviolet Imaging Telescope EIT
Authors: Dere, K. P.; Moses, J. D.; Delaboudinière, J. -P.; Brunaud,
J.; Carabetian, C.; Hochedez, J. -F.; Song, X. Y.; Catura, R. C.;
Clette, F.; Defise, J. -M.
Bibcode: 2000SoPh..195...13D
Altcode:
This paper presents the preflight photometric calibration of the
Extreme-ultraviolet Imaging Telescope (EIT) aboard the Solar and
Heliospheric Observatory (SOHO). The EIT consists of a Ritchey-Chrétien
telescope with multilayer coatings applied to four quadrants of the
primary and secondary mirrors, several filters and a backside-thinned
CCD detector. The quadrants of the EIT optics were used to observe
the Sun in 4 wavelength bands that peak near 171, 195, 284, and 304
Å. Before the launch of SOHO, the EIT mirror reflectivities, the filter
transmissivities and the CCD quantum efficiency were measured and these
values are described here. The instrumental throughput in terms of an
effective area is presented for each of the various mirror quadrant
and filter wheel combinations. The response to a coronal plasma as
a function of temperature is also determined and the expected count
rates are compared to the count rates observed in a coronal hole,
the quiet Sun and an active region.
Title: Correction to “Coronal dimmings and energetic CMEs in
April-May 1998,”
Authors: Thompson, B. J.; Cliver, E. W.; Nitta, N.; Delannée, C.;
Delaboudinière, J. -P.
Bibcode: 2000GeoRL..27.1865T
Altcode:
No abstract at ADS
Title: Coronal dimmings and energetic CMEs in April-May 1998
Authors: Thompson, B. J.; Cliver, E. W.; Nitta, N.; Delannée, C.;
Delaboudinière, J. -P.
Bibcode: 2000GeoRL..27.1431T
Altcode:
We have analyzed the coronal dimmings for seven fast (> 600 km/s)
coronal mass ejections (CMEs) occurring between 23 April and 9 May which
were associated with flares from NOAA active region (AR) 8210. Each
of these CMEs had at least one group of interplanetary radio bursts
associated with them. These dimming regions were identified by their
strong depletion in coronal EUV emission within a half hour of the
estimated time of CME lift-off. They included areas which were as
dark as quiescent coronal holes as well as other regions with weaker
brightness depletions. While the location of the active region and
the associated flare did not correspond well with the coronagraph
observations, we found that the extended dimming areas in these events
generally mapped out the apparent “footprint” of the CME as observed
by white-light coronagraph. We briefly discuss the implications of
these results on models of CME topology.
Title: The STEREO-SECCHI Extreme Ultraviolet Imager
Authors: Wülser, J. -P.; Lemen, J. R.; Tarbell, T. D.; Wolfson,
C. J.; Howard, R. A.; Moses, J. D.; Delaboudinière, J. -P.
Bibcode: 2000SPD....31.0294W
Altcode:
The Extreme Ultraviolet Imager (EUVI) is part of the SECCHI
investigation selected for flight on the STEREO mission. The twin EUVI
telescopes on the two STEREO spacecraft will study the structure and
evolution of the solar corona in three dimensions, and specifically
focus on the initiation and early evolution of coronal mass ejections
(CMEs). The EUVI's 2048 x 2048 pixel detectors will have a full sun
field of view, and will observe in four spectral channels that cover
the 0.1 to 2 MK temperature range. The EUVI's major advance is its
view from two vantage points in space. It will allow it to investigate
the structure of CMEs in three dimensions, while the EUVI's high image
cadence capability will allow it to resolve the CME's initiation and
early evolution.
Title: The STEREO-SECCHI extreme ultraviolet imager.
Authors: Wülser, J. -P.; Lemen, J. R.; Tarbell, T. D.; Wolfson,
C. J.; Howard, R. A.; Moses, J. D.; Delaboudinière, J. -P.
Bibcode: 2000BAAS...32..827W
Altcode:
No abstract at ADS
Title: Observation of the origin of CMEs in the low corona
Authors: Delannée, C.; Delaboudinière, J. -P.; Lamy, P.
Bibcode: 2000A&A...355..725D
Altcode:
The aim of the main observing program with EIT on board SOHO,
is to monitor the whole Sun surface in the Fe xii emission line
at 195 Ä, every 17 minutes. The very beginning of some CMEs can
be observed. We interpret Fe xii images in conjunction with He ii,
Hα and coronagraph observations over a period of 6 days. We find
that 7 prominences produced ejections. An active region produced 9
ejections. Five ejections are seen as dark bubbles propagating above
the solar limb while 9 are seen as dimmings on the solar surface. The
3 other ejections are bright bubbles observed rising up above the
limb. Thirteen of the 17 observed ejections are related to a CME. Two
CMEs of the 15 CMEs observed with LASCO C2 are not related to Fe xii
low corona events. Probably, these CMEs have their origin behind the
limb. Prominences give rise to quite slow CMEs, 50-120 km s-1
while fast CMEs, 110-1000 km s-1, originate close to active
regions. We conclude that CMEs start in the low corona and that large
scale coronal structures reconfigurations occur when these disturbances
propagate outward.
Title: CMEs Observed Continuously from the Lower Corona to the
Far Corona
Authors: Delannée, C.; Delaboudinière, J. -P.; Lamy, P.
Bibcode: 2000AdSpR..26...67D
Altcode:
A campaign of observations with EIT on board SOHO called ``CME watch'',
is designed to observe the whole sun surface in 195 A&ring i.e. in a
Fe XII emission line, every 17 minutes. In order to analyze the events,
we also used He II and coronagraph observations of 97/11/03. By this
way, the very beginning of some CMEs was observed. The ejections
were seen in Fe XII as a dark bubble propagating in the corona
above a prominence, and dimmings produced near an active region and
propagating on the solar surface. Two of the ejections coming from
the active region were produced with a very short time of delay (1
hour). All the ejections were associated to a CME. However, one CME
was not related to a Fe xII low corona event, but maybe this CME had
its origin behind the limb. The CME associated with the prominence
was quite slow (50 km s-1) and the ones associated with
the active region were quite fast (114-490 km s-1). This
analysis permitted a better identification of the different CMEs
appearing in the coronagraph field of view
Title: Eclipse of August 11, 1999: White-light Images and Simultaneous
EIT/SOHO Observations
Authors: Adjabshirizadeh, A.; Baudin, F.; Bocchialini, K.;
Delaboudinière, J. -P.; Grorod, P. -A.; Koutchmy, S.; Laal Aaly,
M.; Lamy, P.; Lochard, J.; Mouette, J.
Bibcode: 1999ESASP.448.1283A
Altcode: 1999ESPM....9.1283A; 1999mfsp.conf.1283A
No abstract at ADS
Title: The Prolate Solar Chromosphere
Authors: Koutchmy, S.; di Folco, E.; Auchere, F.; Baudin, F.;
Delaboudinière, J. -P.; Koutchmy, O.; Noëns, J. -C.; Rondi, S.;
Jimemez, R.; Smartt, R. N.
Bibcode: 1999ESASP.446..385K
Altcode: 1999soho....8..385K
The solar prolateness above h=2Mm is now well established from
measurements performed during the years of solar minimum in HeII, Hα
and K3CaII lines. Low level coronal emissions usually penetrate deep
enough to completely mask this effect and show CH, quite similarly to
the behaviour of the HeI lines (D3; 1083nm) which does not show the
prolateness. We discuss the most recent observations for 1999 given
by a new facility developped at Pic du Midi Observatory (HACO II)
and we compare the results with EIT results in HeII. We also brielfly
discuss the possible interpretations of the prolateness effect. We
favor topological effects implying a large number of nano-flares
and ejecta during the interactions of small-scale low level network
magnetic fields with the more static large-scale magnetic field.
Title: Helical Magnetic Structure Of EUV Polar Plumes
Authors: Veselovsky, I. S.; Zhukov, A. N.; Koutchmy, S.; Delannée,
C.; Delaboudinière, J. -P.
Bibcode: 1999ESASP.446..675V
Altcode: 1999soho....8..675V
The results of an analysis of joint CDS of SOHO and SXT of Yohkoh
observations of a decaying post-flare loop system are presented. The SXT
images were used to explain some peculiar structural features visible
in the examined CDS raster, resulting from the rapid evolution of the
observed system and from the way the CDS rasters are built. The SXT
data was also used to determine the time evolution of the temperature
and the emission measure of the hot part of the system during its
decay. The CDS data, with a very good temperature coverage, contains
a density sensitive line pair of Fe XIV which was used for electron
density analysis and a temperature sensitive line pair of Fe XVI and
Si XII which was used to study the temperature structure of the loop
system. From the integrated intensities of selected lines the emission
measures were calculated. From these measurements we estimated the
filling factor of the loop system in Fe XIV line.
Title: Simultaneous LASCO/1998-Eclipse Observations Of A Large-Scale
Polar Event
Authors: Zhukov, A.; Koutchmy, S.; Lamy, Ph.; Delaboudinière,
J. -P.; Delannée, C.; Bocchialini, K.; Guisard, S.; Filippov, B.;
Veselovsky, I.
Bibcode: 1999ESASP.446..731Z
Altcode: 1999soho....8..731Z
A relatively faint but large scale polar region event was observed
in Aug. 1996 by Boulade et al. 1998 (SoHO SP 404, 217); we first
reconsider this event which has been related to a high latitude
filament disappearance. We continue the study of this class of events by
analyzing the large scale restructuring which occurred above the N-Pole
region at the time of the last Feb. 26, 1998 total solar eclipse. Well
calibrated WL-eclipse images are used to provide the absolute values
of electron densities of the quasi-radial structure appearing at
the feet of the event. This structure can also be considered as a
type of abnormally broad and curved polar plume, a type of activity
already reported in the literature. Unfortunately, the examination
of sequences of EIT images taken at that time seems to indicate that
the roots of the structure are on the back side of the Sun. However
the most impressive effects are seen in the high polar region, at
several radii, based on the analysis of processed Lasco-C2 difference
images. Large proper motions are deduced over density structures. Both
these events confirm that polar regions are indeed showing a new class
of CME activity (possibly related to the Hewish's CMEs), which is seen
inside coronal holes. A whole set of interesting questions is then
appearing to understand the occurrence of a polar CME propagating in
the heart of a large unipolar magnetic region of the corona.
Title: Resonance Scattering of 30.4 NM Chromospheric Radiation by
Coronal Singly Ionized Helium Observed with EIT
Authors: Delaboudinière, J. P.
Bibcode: 1999SoPh..188..259D
Altcode:
A diffuse emission is observed above the solar limb in the `304 Å'
channel of the Extreme-Ultraviolet Imaging Telescope (EIT) onboard
the SOHO spacecraft. Part of this emission is attributed to the
presence of residual singly-ionized helium in the solar corona,
which resonantly scatters the intense helium `Lyman alpha' radiation
of the chromosphere. This emission can be distinguished from other
coronal emissions in the EIT bandpass. Maps of the helium ion density
integrated along the line of sight are derived. These agree well with
models in the low latitude, closed magnetic field regions of the solar
corona. However, the helium ions' abundance seems to be enhanced in
the polar, open field regions above coronal holes. This may be related
to acceleration processes of the fast solar wind close to the Sun.
Title: Equivalent focal length measurements
Authors: Artzner, Guy E.; Auchere, Frederic; Delaboudiniere,
Jean-Pierre; Hochedez, Jean-Francois E.
Bibcode: 1999SPIE.3737...32A
Altcode:
Converting linear coordinates in the plane of the detector of
an astronomical instrument to celestial coordinates involves in
principle the equivalent focal length of the instrument. However,
most methods in astrometry manage to reduce observations in a global
manner without actually measuring a focal length. We point out a case
for solar space observations where the long term stability of angular
distance measurements is better than the ground calibration of the
angular value of a pixel. We report and discuss this ground calibration.
Title: SOHO/EIT Observations of the 1997 April 7 Coronal Transient:
Possible Evidence of Coronal Moreton Waves
Authors: Thompson, B. J.; Gurman, J. B.; Neupert, W. M.; Newmark,
J. S.; Delaboudinière, J. -P.; Cyr, O. C. St.; Stezelberger, S.;
Dere, K. P.; Howard, R. A.; Michels, D. J.
Bibcode: 1999ApJ...517L.151T
Altcode:
We report observations obtained with the Extreme ultraviolet
Imaging Telescope (EIT) on board SOHO of a large-scale coronal
transient propagating across the disk of the Sun at a speed of 250 km
s-1, in apparent association with a flare and coronal mass
ejection. The observations consist of a series of images taken in the
Fe XII 195 Å bandpass at an average cadence of 15 minutes. A visible
increase in coronal emission propagates away from the erupting region,
traveling across most of the solar disk in less than an hour. As the
wave propagates through the ambient corona, its path is not homogeneous,
and it is less observable near strong magnetic features such as
active regions and magnetic neutral lines. The characteristics of
this event appear to be representative of several other ``EIT waves,''
which we identify as strong candidates for the coronal manifestation
of Moreton waves.
Title: LASCO and EIT Observations of Helical Structure in Coronal
Mass Ejections
Authors: Dere, K. P.; Brueckner, G. E.; Howard, R. A.; Michels, D. J.;
Delaboudiniere, J. P.
Bibcode: 1999ApJ...516..465D
Altcode:
Observations of coronal mass ejections (CMEs) by the Large Angle
Spectrometric Coronagraph (LASCO) on the Solar and Heliospheric
Observatory (SOHO) show a significant fraction with circular intensity
patterns. In the past, these would have been called ``disconnection''
events, but we suggest that these are evidence of CMEs containing
helical magnetic flux ropes that are often central to many theoretical
models of CMEs and have been observed in magnetic clouds near
1 AU. Three examples are examined in detail with the LASCO and
Extreme-Ultraviolet Imaging Telescope (EIT) data sets, which provide
observations from their initiation through 30 Rsolar.
Title: Three-dimensional Stereoscopic Analysis of Solar Active
Region Loops. I. SOHO/EIT Observations at Temperatures of (1.0-1.5)
× 106 K
Authors: Aschwanden, Markus J.; Newmark, Jeffrey S.; Delaboudinière,
Jean-Pierre; Neupert, Werner M.; Klimchuk, J. A.; Gary, G. Allen;
Portier-Fozzani, Fabrice; Zucker, Arik
Bibcode: 1999ApJ...515..842A
Altcode:
The three-dimensional structure of solar active region NOAA 7986
observed on 1996 August 30 with the Extreme-Ultraviolet Imaging
Telescope (EIT) on board the Solar and Heliospheric Observatory
(SOHO) is analyzed. We develop a new method of dynamic stereoscopy to
reconstruct the three-dimensional geometry of dynamically changing
loops, which allows us to determine the orientation of the mean
loop plane with respect to the line of sight, a prerequisite to
correct properly for projection effects in three-dimensional loop
models. With this method and the filter-ratio technique applied
to EIT 171 and 195 Å images we determine the three-dimensional
coordinates [x(s), y(s), z(s)], the loop width w(s), the electron
density ne(s), and the electron temperature Te(s)
as a function of the loop length s for 30 loop segments. Fitting the
loop densities with an exponential density model ne(h)
we find that the mean of inferred scale height temperatures,
Tλe=1.22+/-0.23 MK, matches closely that of EIT
filter-ratio temperatures, TEITe=1.21+/-0.06
MK. We conclude that these cool and rather large-scale loops (with
heights of h~30-225 Mm) are in hydrostatic equilibrium. Most of the
loops show no significant thickness variation w(s), but we measure
for most of them a positive temperature gradient (dT/ds>0) across
the first scale height above the footpoint. Based on these temperature
gradients we find that the conductive loss rate is about 2 orders of
magnitude smaller than the radiative loss rate, which is in strong
contrast to hot active region loops seen in soft X-rays. We infer a
mean radiative loss time of τrad~40 minutes at the loop
base. Because thermal conduction is negligible in these cool EUV
loops, they are not in steady state, and radiative loss has entirely
to be balanced by the heating function. A statistical heating model
with recurrent heating events distributed along the entire loop can
explain the observed temperature gradients if the mean recurrence time
is <~10 minutes. We computed also a potential field model (from
SOHO/MDI magnetograms) and found a reasonable match with the traced
EIT loops. With the magnetic field model we determined also the height
dependence of the magnetic field B(h), the plasma parameter β(h),
and the Alfvén velocity vA(h). No correlation was found
between the heating rate requirement EH0 and the magnetic
field Bfoot at the loop footpoints.
Title: Evolution of Chromospheric Structures: How Chromospheric
Structures Contribute to the Solar HE II 30.4 Nanometer Irradiance
and Variability
Authors: Worden, John; Woods, Thomas N.; Neupert, Werner M.;
Delaboudinière, Jean-Pierre
Bibcode: 1999ApJ...511..965W
Altcode:
The bright He II 30.4 nm solar emission is an important energy source
for ionization and heating of the Earth's upper atmosphere. The analysis
of the Solar and Heliospheric Observatory (SOHO) Extreme-Ultraviolet
Imaging Telescope (EIT) He II 30.4 nm images provides an improved
understanding of how the solar surface structures, i.e., plage,
enhanced network (plage remnants), active network, and the quiet
chromosphere, contribute to the solar He II 30.4 nm irradiance and
its variability. We first normalize the intensities of each image
to the background quiet-chromosphere intensity with a global fit
that preferentially weights network cell intensities. The resulting
quiet-chromosphere intensity scale is stable to within 0.7% (1 σ)
over the 2 yr data set. The plage, enhanced-network, active-network,
and quiet-chromosphere structures are then identified on each EIT
He II image with an algorithm that uses criteria of intensity,
size, filling factor, and continuity. This decomposition leads to
time series of structure area and integrated intensity, their spatial
distribution on the solar disk, and their intensity contrast relative to
the quiet-chromosphere intensity; thus, these time series show how the
solar surface structures contribute to the He II 30.4 nm irradiance. For
example, we find that the active network contributes as much as the
plage and enhanced network to the solar He II 30.4 nm irradiance
variability during solar minimum. Conversely, the quiet-chromosphere
irradiance does not vary during this time period; thus we conclude that
long-term He II 30.4 nm irradiance variations can be traced purely
to magnetic activity during this time period. We also find that the
plage, enhanced-network, active-network, and quiet-network intensity
contrasts, relative to the quiet chromosphere and averaged over the
full area of each structure, are 4.8, 3.3, 2.1, and 1.6, respectively,
and these contrasts remain essentially constant with time.
Title: Eruptive filament of May 31, 1997, observed by SOHO.
Authors: Schmieder, B.; Heinzel, P.; Vial, J. -C.; Delaboudinière,
J. -P.; Delannée, C.
Bibcode: 1999joso.proc..147S
Altcode:
In the frame of the SUMER/CDS Joint Programme (JOP 17) the authors
have detected the four Lyman lines in an erupting filament. The
strong self-absorption in these lines, already reported for quiescent
filaments, is still present in this highly dynamical event, but the
authors observe a significant red asymmetry in the intensities of the
two peaks. They ascribe it to an upward bulk motion of the filament,
which they can actually see on a series of EIT images taken in the
Fe XII line. Both sets of observations can lead to a determination
of the velocity vector. The Doppler velocities are also derived from
other lines detected by SUMER/CDS and can be correlated with the
observations of the Pic-du-Midi MSDP obtained for this event. The
filament eruption was also well observed by other GBO instruments in
the Hα line (Meudon and Ondřejov).
Title: CME observed continuously from the lower corona to the far
corona (CME's onset on November 3, 1997).
Authors: Delannée, C.; Delaboudinière, J. -P.; Lamy, P.
Bibcode: 1999joso.proc..162D
Altcode:
A program of observations with EIT on board SOHO, is to observe the
whole sun surface in 195 Å, i.e. in a Fe XII emission line, every
17 minutes. The very beginning of some CMEs is observed. The authors
correlate each Fe XII observation with He II, Hα and coronagraph
observations on 97/11/03 and 97/11/04. They found that three prominences
were ejected, and that an active region produced 4 ejections. The
ejections are dark bubbles propagating above the sun limb, and dimmings
propagating on the solar surface in Fe XII. They each produced an
associated CME. One CME was not correlated to a Fe XII low corona
event. Maybe, this CME had its origin behind the limb. The prominence
gave a quite slow CME, i.e. about 50 km s-1 and the active
region produced some quite fast CMEs, i.e. about 300 km s-1.
Title: Observations of Correlated White-Light and Extreme-Ultraviolet
Jets from Polar Coronal Holes
Authors: Wang, Y. -M.; Sheeley, N. R., Jr.; Socker, D. G.; Howard,
R. A.; Brueckner, G. E.; Michels, D. J.; Moses, D.; St. Cyr, O. C.;
Llebaria, A.; Delaboudinière, J. -P.
Bibcode: 1998ApJ...508..899W
Altcode:
Time-lapse sequences of white-light images recorded with the Large
Angle Spectrometric Coronagraph (LASCO) on the Solar and Heliospheric
Observatory (SOHO) frequently show long, narrow structures moving
outward over the Sun's polar regions at high apparent speeds. By
comparing the LASCO observations with Fe XII λ195 spectroheliograms
made with the Extreme-ultraviolet Imaging Telescope (EIT) on SOHO
between 1997 April and 1998 February, we have identified 27 correlated
white-light and extreme-ultraviolet (EUV) jet events. In each case,
the EUV jet was observed near the limb of the polar coronal hole 20-60
minutes before the corresponding white-light jet was registered in the
coronagraph's 2-6 R⊙ field of view. The jets originate
near flaring EUV bright points and are presumably triggered by field
line reconnection between magnetic bipoles and neighboring unipolar
flux. The leading edges of the white-light jets propagate outward at
speeds of 400-1100 km s-1, whereas the bulk of their material
travels at much lower velocities averaging around 250 km s-1
at heliocentric distances of 2.9-3.7 R⊙. These lower
velocities may reflect the actual outflow speeds of the background
polar wind.
Title: Observations of Coronal Structures Above an Active Region by
EIT and Implications for Coronal Energy Deposition
Authors: Neupert, W. M.; Newmark, J.; Delaboudinière, J. -P.;
Thompson, B. J.; Catura, R. C.; Moses, J. D.; Gurman, J. B.;
Portier-Fozzani, F.; Gabriel, A. H.; Artzner, G.; Clette, F.; Cugnon,
P.; Maucherat, A. J.; Defise, J. M.; Jamar, C.; Rochus, P.; Dere,
K. P.; Howard, R. A.; Michels, D. J.; Freeland, S.; Lemen, J. R.;
Stern, R. A.
Bibcode: 1998SoPh..183..305N
Altcode:
Solar EUV images recorded by the EUV Imaging Telescope (EIT) on SOHO
have been used to evaluate temperature and density as a function of
position in two largescale features in the corona observed in the
temperature range of 1.0-2.0 MK. Such observations permit estimates
of longitudinal temperature gradients (if present) in the corona and,
consequently, estimates of thermal conduction and radiative losses
as a function of position in the features. We examine two relatively
cool features as recorded in EIT's Fe ix/x (171 Å) and Fe xii (195 Å)
bands in a decaying active region. The first is a long-lived loop-like
feature with one leg, ending in the active region, much more prominent
than one or more distant footpoints assumed to be rooted in regions of
weakly enhanced field. The other is a near-radial feature, observed
at the West limb, which may be either the base of a very high loop
or the base of a helmet streamer. We evaluate energy requirements to
support a steady-state energy balance in these features and find in
both instances that downward thermal conductive losses (at heights
above the transition region) are inadequate to support local radiative
losses, which are the predominant loss mechanism. The requirement that a
coronal energy deposition rate proportional to the square of the ambient
electron density (or pressure) is present in these cool coronal features
provides an additional constraint on coronal heating mechanisms.
Title: The prolate solar chromosphere
Authors: Auchere, F.; Boulade, S.; Koutchmy, S.; Smartt, R. N.;
Delaboudiniere, J. P.; Georgakilas, A.; Gurman, J. B.; Artzner, G. E.
Bibcode: 1998A&A...336L..57A
Altcode:
We present a comparative analysis of the chromospheric solar
limb prolateness, using strictly simultaneous H_alpha ground-based
observations and Heriptsize{II} space-based observations. The typical
prolateness is found to be Delta D/D=5.5*E(-3) in Heriptsize{II}
and 1.2*E(-3) in H_alpha . The first measurements in the 30.4 nm
Heriptsize{II} line over a period of two years, as well as coronal
data, are discussed to explore further the origin of the prolateness
and its possible consequences.
Title: Geomagnetic storms caused by coronal mass ejections (CMEs):
March 1996 through June 1997
Authors: Brueckner, G. E.; Delaboudiniere, J. -P.; Howard, R. A.;
Paswaters, S. E.; St. Cyr, O. C.; Schwenn, R.; Lamy, P.; Simnett,
G. M.; Thompson, B.; Wang, D.
Bibcode: 1998GeoRL..25.3019B
Altcode:
(1) All but two geomagnetic storms with Kp ≥ 6 during the operating
period (March 1996 through June 1997) of the Large Angle Spectroscopic
Coronagraph (LASCO) experiment on the Solar and Heliospheric Observatory
(SOHO) spacecraft can be traced to Coronal Mass Ejections (CMEs). (2)
These geomagnetic storms are not related to high speed solar wind
streams. (3) The CMEs which cause geomagnetic effects, can be classified
into two categories: Halo events and toroidal CMEs. (4) The CMEs are
accompanied by Coronal Shock Waves as seen in the Extreme Ultraviolet
Imaging Telescope (EIT) Fe XII images. (5) Some CMEs are related to
flares, others are not. (6) In many cases, the travel time between
the explosion on the Sun and the maximum geomagnetic activity is about
80 hours.
Title: Evidence for multiple ejecta: April 7-11, 1997, ISTP Sun-Earth
connection event
Authors: Berdichevsky, D.; Bougeret, J. -L.; Delaboudinière, J. -P.;
Fox, N.; Kaiser, M.; Lepping, R.; Michels, D.; Plunkett, S.; Reames,
D.; Reiner, M.; Richardson, I.; Rostoker, G.; Steinberg, J.; Thompson,
B.; von Rosenvinge, T.
Bibcode: 1998GeoRL..25.2473B
Altcode:
Evidence is presented that the enhanced geomagnetic activity, on
April 10-11, 1997, was caused by one of two ejecta that left the
Sun at ≈ 14 UT on April 7. This ejecta was not directly detected
at the Earth. The evidence for this interpretation is based on WIND
spacecraft observations in the solar wind (SW). It is consistent with:
(i) measured velocities of the coronal mass ejections from the SOHO
coronagraph; (ii) the initial propagation speed of the shock generated
in this event, estimation from type II radio burst observations from the
WAVES instrument on WIND, and (iii) the time profile of energetic ions
observed by EPACT on WIND. This locally unobserved ejecta (moving at 600
to 700 kms-1) generated a fast shock which accelerated ions
to several tens of MeV/amu. The inferred passage of the first ejecta
close to Earth (on April 10 to 11) is based on the observation of an
interplanetary shock (IS) ahead of a field and plasma compressional
region where the draping of the SW flow and possibly the changes in
the direction of the IMF are consistent with a location northward of a
faster ejecta. This ejecta was responsible for disturbed SW conditions
including approximately ten hours of southward orientation of the
interplanetary magnetic field (IMF) and a ram pressure many times
above normal. The slower moving ejecta was directed toward Earth and
was observed with WIND from about 0550 until 1500 UT on April 11. It
had a strong northward IMF and produced density enhancements which
elevated the ram pressure to more than four times above normal.
Title: Statistical analysis of solar bright points observed with
the SOHO spacecraft.
Authors: Régnier, S.; Bocchialini, K.; Vial, J. -C.; Delaboudinière,
J. -P.; Thompson, W.
Bibcode: 1998CRASB.326..211R
Altcode: 1998CR2...326..211R
Bright points, small and short lifetime structures, appear permanently
in the atmosphere and could be associated with magnetic reconnections,
potential sources of coronal heating. Such structures have been
observed with the coronal instruments on-board SOHO and a statistical
analysis was carried out in order to find the signature of very small
scale structures.
Title: The polar extension of the solar chromosphere
Authors: Auchère, F.; Delaboudinière, J. P.; Koutchmy, S.;
Boulade, S.
Bibcode: 1998ESASP.421..245A
Altcode: 1998sjcp.conf..245A
No abstract at ADS
Title: 3D-Stereoscopic Analysis of Solar Active Region Loops Observed
with SOHO/EIT
Authors: Aschwanden, M. J.; Newmark, J. S.; Delaboudiniere, J. -P.;
Neupert, W. M.; Klimchuk, J. A.; Gary, G. Allen; Portier-Fozzani,
F.; Zucker, A.
Bibcode: 1998cee..workE..19A
Altcode:
The three-dimensional (3D) structure of solar active region NOAA
7986 observed on 1996 August 30 with the Extrem-ultraviolet Imaging
Telescope (EIT) onboard the Solar and Heliospheric Observatory
(SoHO) is analyzed. We develop a new method of Dynamic Stereoscopy to
reconstruct the 3D geometry of dynamically changing loops, which allows
us to determine the orientation of the loop plane with respect to
the line-of-sight, a prerequisite to correct properly for projection
effects in 3D loop models. With this method and the filter-ratio
technique applied to EIT 171 angle and 195 angle images we determine
the 3D coordinates [x(s),y(s),z(s)], the loop width w(s), the electron
density n_e(s), and the electron temperature T_e(s) as function of
the loop length s for 30 loop segments. Fitting the loop densities
with an exponential density model n_e(h) we find that the mean of
inferred scale height temperatures, T_elambda = 1.22 plus or
minus 0.23 MK, matches closely that of EIT filter-ratio temperatures,
T_eEIT = 1.21 plus or minus 0.06 MK. We conclude that these
cool and rather large-scale loops (with heights of h ~30-225 Mm), which
dominate the EIT 171 angle images, are in hydrostatic equilibrium. Most
of the loops show no significant thickness variation w(s), but we can
measure for most of them a positive temperature gradient (dT/ds >
0) across the first scale height above the footpoint. Based on these
temperature gradients we find that the conductive loss rate is about
two orders of magnitude smaller than the radiative loss rate, which is
in strong contrast to hot active region loops seen in SXR. We infer a
mean radiative loss time of τrad ~40 minutes. For steady
state models, the heating rate has to balance the radiative loss,
i.e. the heating rate has to scale with the squared density (E_H
propto n_e^2). From potential-field extrapolations we determine also
the magnetic field strength B(s), the plasma beta-parameter beta(s),
and the Alfven velocity v_A(s) along the loops, and discuss the findings
in the context of coronal heating models.
Title: About polar ejection events and surges
Authors: Loucif, M. L.; Koutchmy, S.; Stellmacher, G.; Georgakilas,
A.; Bocchialini, K.; Delaboudinière, J. -P.
Bibcode: 1998ESASP.421..299L
Altcode: 1998sjcp.conf..299L
No abstract at ADS
Title: EUV and Microwave Observations of a Filament
Authors: Chiuderi-Drago, F.; Bocchialini, K.; Lamartinie, S.;
Vial, J. -C.; Bastian, T.; Alissandrakis, C. E.; Harrison, R.;
Delaboudiniere, J. -P.; Lemaire, P.
Bibcode: 1998ASPC..150...55C
Altcode: 1998IAUCo.167...55C; 1998npsp.conf...55C
No abstract at ADS
Title: LASCO/EIT Observations of Coronal Mass Ejections from
Large-Scale Filament Channels
Authors: Plunkett, S. P.; Dere, K. P.; Howard, R. A.; Michels, D. J.;
Brueckner, G. E.; Thompson, B. J.; Delaboudiniere, J. -P.
Bibcode: 1998ASPC..150..475P
Altcode: 1998npsp.conf..475P; 1998IAUCo.167..475P
No abstract at ADS
Title: Spicules and Macrospicules: Simultaneous Hα and He II (304
Å) Observations
Authors: Georgakilas, A. A.; Dara, H.; Zachariadis, Th.; Alissandrakis,
C. E.; Koutchmy, S.; Delannée, C.; Delaboudinière, J. -P.; Hochedez,
J. -F.
Bibcode: 1998ASPC..155..376G
Altcode: 1998sasp.conf..376G
No abstract at ADS
Title: European Plans for the Solar/Heliospheric Stereo Mission
Authors: Bothmer, V.; Bougeret, J. -L.; Cargill, P.; Davila, J.;
Delaboudiniere, J. -P.; Harrison, R.; Koutchmy, S.; Liewer, P.;
Maltby, P.; Rust, D.; Schwenn, R.
Bibcode: 1998ESASP.417..145B
Altcode: 1998cesh.conf..145B
No abstract at ADS
Title: Velocity Fields of a Filament Region Observed with Ground-Based
Telescopes and from SOHO
Authors: Mein, P.; Schmieder, B.; Malherbe, J. -M.; Wiik, J. E.;
Engvold, O.; Brekke, P.; Zirker, J. B.; Poland, A. I.; Delaboudiniere,
J. -P.; Staiger, J.
Bibcode: 1998ASPC..150..135M
Altcode: 1998npsp.conf..135M; 1998IAUCo.167..135M
No abstract at ADS
Title: Polar jets and plasmoids:Results from JOP 57
Authors: Delannee, C.; Koutchmy, S.; Delaboudiniere, J. -P.; Hochedez,
J. -F.; Vial, J. -C.; Dara, H.; Georgakilas, A.
Bibcode: 1998ESASP.421..129D
Altcode: 1998sjcp.conf..129D
No abstract at ADS
Title: Solar Energetic Particle Events and Coronal Mass Ejections:
New Insights from SOHO
Authors: Bothmer, V.; Posner, A.; Kunow, H.; Müller-Mellin, R.;
Herber, B.; Pick, M.; Thompson, B. J.; Delaboudinière, J. -P.;
Brueckner, G. E.; Howard, R. A.; Michels, D. J.; Cyr, C. St.; Szabo,
A.; Hudson, H. S.; Mann, G.; Classen, H. -T.; McKenna-Lawlor, S.
Bibcode: 1997ESASP.415..207B
Altcode: 1997cpsh.conf..207B
No abstract at ADS
Title: Fluxes of MeV Particles at Earth's Orbit and their Relationship
with the Global Structure of the Solar Corona: Observations from SOHO
Authors: Posner, A.; Bothmer, V.; Kunow, H.; Herber, B.;
Müller-Mellin, R.; Delaboudinière, J. -P.; Thompson, B. J.;
Brückner, G. E.; Howard, R. A.; Muchels, D. J.
Bibcode: 1997ESASP.415..377P
Altcode: 1997cpsh.conf..377P
No abstract at ADS
Title: Solar Active Region Movies seen by the SOHO Extreme-ultraviolet
Telescope
Authors: Newmark, J. S.; Thompson, B.; Gurman, J. B.; Delaboudiniere,
J. P.; Aschwanden, Markus; Mason, Helen
Bibcode: 1997AAS...191.7307N
Altcode: 1997BAAS...29.1321N
The Extreme-ultraviolet Imaging Telescope (EIT) on board the SOHO (SOlar
and Heliospheric Observatory) satellite provides wide-field images of
the corona and transition region on the solar disc and up to 1.4 solar
radii above the limb. Its normal incidence multilayer-coated optics
select spectral emission lines from FeIX (171 Ang), FeXII (195 Ang),
FeXV (284 Ang), and HeII (304 Ang) with 2.6 arcsecond resolution which
allow us to describe Solar activity over a wide temperature range. EIT
is providing unique EUV observations of the structure and evolution of
active regions. Here we show movies of active region 8059 from July
3-10, 1997. The high temporal variability of the AR loops is very
evident. Initial temperature and density diagnostics are explored as
well as a comparison with diagnostics from the SOHO-CDS instrument.
Title: EIT Observations of the Extreme Ultraviolet Sun
Authors: Moses, D.; Clette, F.; Delaboudinière, J. -P.; Artzner,
G. E.; Bougnet, M.; Brunaud, J.; Carabetian, C.; Gabriel, A. H.;
Hochedez, J. F.; Millier, F.; Song, X. Y.; Au, B.; Dere, K. P.; Howard,
R. A.; Kreplin, R.; Michels, D. J.; Defise, J. M.; Jamar, C.; Rochus,
P.; Chauvineau, J. P.; Marioge, J. P.; Catura, R. C.; Lemen, J. R.;
Shing, L.; Stern, R. A.; Gurman, J. B.; Neupert, W. M.; Newmark,
J.; Thompson, B.; Maucherat, A.; Portier-Fozzani, F.; Berghmans, D.;
Cugnon, P.; Van Dessel, E. L.; Gabryl, J. R.
Bibcode: 1997SoPh..175..571M
Altcode:
The Extreme Ultraviolet Imaging Telescope (EIT) on board the SOHO
spacecraft has been operational since 2 January 1996. EIT observes
the Sun over a 45 x 45 arc min field of view in four emission line
groups: Feix, x, Fexii, Fexv, and Heii. A post-launch determination
of the instrument flatfield, the instrument scattering function, and
the instrument aging were necessary for the reduction and analysis
of the data. The observed structures and their evolution in each
of the four EUV bandpasses are characteristic of the peak emission
temperature of the line(s) chosen for that bandpass. Reports on the
initial results of a variety of analysis projects demonstrate the range
of investigations now underway: EIT provides new observations of the
corona in the temperature range of 1 to 2 MK. Temperature studies of
the large-scale coronal features extend previous coronagraph work
with low-noise temperature maps. Temperatures of radial, extended,
plume-like structures in both the polar coronal hole and in a low
latitude decaying active region were found to be cooler than the
surrounding material. Active region loops were investigated in detail
and found to be isothermal for the low loops but hottest at the loop
tops for the large loops.
Title: EIT and LASCO Observations of the Initiation of a Coronal
Mass Ejection
Authors: Dere, K. P.; Brueckner, G. E.; Howard, R. A.; Koomen, M. J.;
Korendyke, C. M.; Kreplin, R. W.; Michels, D. J.; Moses, J. D.;
Moulton, N. E.; Socker, D. G.; St. Cyr, O. C.; Delaboudinière, J. P.;
Artzner, G. E.; Brunaud, J.; Gabriel, A. H.; Hochedez, J. F.; Millier,
F.; Song, X. Y.; Chauvineau, J. P.; Marioge, J. P.; Defise, J. M.;
Jamar, C.; Rochus, P.; Catura, R. C.; Lemen, J. R.; Gurman, J. B.;
Neupert, W.; Clette, F.; Cugnon, P.; Van Dessel, E. L.; Lamy, P. L.;
Llebaria, A.; Schwenn, R.; Simnett, G. M.
Bibcode: 1997SoPh..175..601D
Altcode:
We present the first observations of the initiation of a coronal mass
ejection (CME) seen on the disk of the Sun. Observations with the EIT
experiment on SOHO show that the CME began in a small volume and was
initially associated with slow motions of prominence material and a
small brightening at one end of the prominence. Shortly afterward,
the prominence was accelerated to about 100 km s-1 and
was preceded by a bright loop-like structure, which surrounded an
emission void, that traveled out into the corona at a velocity of
200-400 km s-1. These three components, the prominence,
the dark void, and the bright loops are typical of CMEs when seen at
distance in the corona and here are shown to be present at the earliest
stages of the CME. The event was later observed to traverse the LASCO
coronagraphs fields of view from 1.1 to 30 R⊙. Of particular interest
is the fact that this large-scale event, spanning as much as 70 deg in
latitude, originated in a volume with dimensions of roughly 35" (2.5
x 104 km). Further, a disturbance that propagated across
the disk and a chain of activity near the limb may also be associated
with this event as well as a considerable degree of activity near the
west limb.
Title: Association of Extreme-Ultraviolet Imaging Telescope (EIT)
Polar Plumes with Mixed-Polarity Magnetic Network
Authors: Wang, Y. -M.; Sheeley, N. R.; Dere, K. P.; Duffin, R. T.;
Howard, R. A.; Michels, D. J.; Moses, J. D.; Harvey, J. W.; Branston,
D. D.; Delaboudinière, J. -P.; Artzner, G. E.; Hochedez, J. F.;
Defise, J. M.; Catura, R. C.; Lemen, J. R.; Gurman, J. B.; Neupert,
W. M.; Newmark, J.; Thompson, B.; Maucherat, A.; Clette, F.
Bibcode: 1997ApJ...484L..75W
Altcode:
SOHO EIT spectroheliograms showing the polar coronal holes during the
present sunspot minimum are compared with National Solar Observatory
(Kitt Peak) magnetograms taken in Fe I λ8688 and Ca II λ8542. The
chromospheric λ8542 magnetograms, obtained on a routine, near-daily
basis since 1996 June, reveal the Sun's strong polar fields with
remarkable clarity. We find that the Fe IX λ171 polar plumes occur
where minority-polarity flux is in contact with flux of the dominant
polarity inside each polar hole. Moreover, the locations of ``plume
haze'' coincide approximately with the patterns of brightened He
II λ304 network within the coronal hole. The observations appear
to be consistent with mechanisms of plume formation involving
magnetic reconnection between unipolar flux concentrations and nearby
bipoles. The fact that minority-polarity fields constitute only a small
fraction of the total magnetic flux within the polar holes suggests
that plumes are not the main source of the high-speed polar wind.
Title: EIT and LASCO observations of the initiation of a coronal
mass ejection
Authors: Dere, K.; Brueckner, G. E.; Delaboudiniere, J. -P.
Bibcode: 1997SPD....28.0502D
Altcode: 1997BAAS...29R.908D
We present the first observations of the initiation of a coronal mass
ejection (CME) seen on the disk of the Sun. Observations with the EIT
experiment on SOHO show that the CME began in a small volume and was
initially associated with slow motions of prominence material and a
small brightening at one end of the prominence. Shortly afterward,
the prominence was accelerated to about 200 kms and was preceded by
a bright loop-like structure, which surrounded an emission void,
that traveled out into the corona at a velocity of 400 kms. These
three components, the prominence, the dark void, and the bright loops
are typical of CMEs when seen at distance in the corona and here are
shown to be present at the earliest stages of the CME. The event was
later observed to traverse the LASCO coronagraphs fields of view from
1.1 to 30 R_⊙. Of particular interest is the fact that this large
scale event, spanning as much as 70 degrees in latitude, originated
in a volume with dimensions of roughly 35" (2.5 x 10(4) km). Further,
a disturbance that propagated across the disk and a chain of activity
near the limb may also be associated with this event as well as a
considerable degree of activity near the west limb.
Title: Observations of Coronal Features by EIT above an Active Region
by EIT and Implications for Coronal Heating
Authors: Neupert, W. M.; Newmark, J.; Thompson, B. J.; Catura, R.;
Moses, J. D.; Portier-Fozzani, F.; Delaboudiniere, J. P.; Gabriel, A.;
Artzner, G.; Clette, F.; Cugnon, P.; Maucherat, A.; Defise, J. M.;
Jamar, C.; Rochus, P.; Howard, R.; Michels, D.; Dere, K.; Freeland,
S.; Lemen, J.; Stern, R.; Gurman, J.
Bibcode: 1997SPD....28.0115N
Altcode: 1997BAAS...29..881N
The EUV Imaging Telescope (EIT) on the SOHO provides the capability
for multi-wavelength imaging of the corona in four spectral bands,
centered at 171, 195, 284, and 304 Angstroms, using multilayer telescope
technology. These bands encompass coronal temperatures from 1 MK
to 2.5 MK as well as the upper chromosphere, at about 60,000 K. In
particular, nearly simultaneous imaging in the 171 and 195 Angstrom
bands, the former including major Fe IX and Fe X emission lines, the
latter including a strong Fe XII line, provides a capability to infer
the morphology and characteristics of the corona at temperatures of
1.0 - 1.7 MK. We have examined the corona in this temperature range
over an active region observed from SOHO from May - September, 1996 and
find that low-lying loops (below a density scale height of 75,000 km,
characteristic of Fe X) vary little in brightness and temperature along
their length. For features extending to greater heights, however, both
brightness gradients and temperature gradients are observed. Preliminary
analysis of the observations when the region was on the West limb
on September 30 indicates a small positive temperature gradient of
approximately 0.5 K/km in one loop system that extended above 100,000
km. On the other hand, a nearly radial feature extending to the edge of
the EIT FOV was isothermal or had at most a slight negative temperature
gradient. Such measurements may have application to the modeling of
coronal loops and streamers and the processes of coronal heating and
solar wind acceleration.
Title: Imaging the solar corona in the EUV
Authors: Delaboudiniere, J. -P.; Stern, R. A.; Maucherat, A.;
Portier-Fozzani, F.; Neupert, W. M.; Gurman, J. B.; Catura, R. C.;
Lemen, J. R.; Shing, L.; Artzner, G. E.; Brunaud, J.; Gabriel, A. H.;
Michels, D. J.; Moses, J. D.; Au, B.; Dere, K. P.; Howard, R. A.;
Kreplin, R.; Defise, J. M.; Jamar, C.; Rochus, P.; Chauvineau, J. P.;
Marioge, J. P.; Clette, F.; Cugnon, P.; van Dessel, E. L.
Bibcode: 1997AdSpR..20.2231D
Altcode:
The SOHO (SOlar and Heliospheric Observatory) satellite was launched on
December 2nd 1995. After arriving at the Earth-Sun (L1) Lagrangian point
on February 14th 1996, it began to continuously observe the Sun. As
one of the instruments onboard SOHO, the EIT (Extreme ultraviolet
Imaging Telescope) images the Sun's corona in 4 EUV wavelengths. The
He II filter at 304 A˚ images the chromosphere and the base of the
transition region at a temperature of 5 - 8 x 10^4 K; the Fe IX-X
filter at 171 A˚ images the corona at a temperature of ~ 1.3 x 10^6 K;
the Fe XII filter at 195 A˚ images the quiet corona outside coronal
holes at a temperature of ~ 1.6 x 10^6 K; and the Fe XV filter at 284
A˚ images active regions with a temperature of ~ 2.0 x 10^6 K. About
5000 images have been obtained up to the present. In this paper,
we describe also some aspects of the telescope and the detector
performance for application in the observations. Images and movies
of all the wavelengths allow a look at different phenomena present in
the Sun's corona, and in particular, magnetic field reconnection.
Title: First Results from SOHO on Waves Near the Solar Transition
Region
Authors: Steffens, S.; Deubner, F. -L.; Fleck, B.; Wilhelm, K.;
Schuhle, U.; Curdt, W.; Harrison, R.; Gurman, J.; Thompson, B. J.;
Brekke, P.; Delaboudiniere, J. -P.; Lemaire, P.; Hessel, B.; Rutten,
R. J.
Bibcode: 1997ASPC..118..284S
Altcode: 1997fasp.conf..284S
We present first results from simultaneous observations with the
CDS, EIT and SUMER instruments {please see Solar Physics 162 (1995)
for a description of the instruments} onboard SOHO and the VTT at
Tenerife. Our aim is to study the wave propagation, shock formation,
and transmission properties of the upper chromosphere and transition
region. The preliminary results presented here include the variation
of velocity power spectra with height, difference in power between
internetwork and network regions, and variations in mean flows displayed
by different spectral lines.
Title: SOHO EIT Carrington Maps from Synoptic Full-Disk Data
Authors: Thompson, B. J.; Newmark, J. S.; Gurman, J. B.;
Delaboudiniere, J. P.; Clette, F.; Gibson, S. E
Bibcode: 1997ESASP.404..779T
Altcode: 1997cswn.conf..779T
No abstract at ADS
Title: Coronal EUV and Radio Variability and Heating
Authors: Krucker, S.; Benz, A. O.; Delaboudinière, J. -P.
Bibcode: 1997ESASP.404..465K
Altcode: 1997cswn.conf..465K
No abstract at ADS
Title: EIT and LASCO Observations of the Initiation of a Coronal
Mass Ejection
Authors: Dere, K. P.; Brueckner, G. E.; Howard, R. A.; Koomen, M. J.;
Korendyke, C. M.; Michels, D. J.; Moses, J. D.; Moulton, N. E.; Socker,
D. G.; Delaboudiniere, J. P.; Hochedez, J. F.; Lamy, P. L.; Schwenn,
R.; Simnett, G. M.; Defise, J. M.; Catura, R. C.
Bibcode: 1997IAUJD..19E..18D
Altcode:
We present the first observations of the initiation of a corona mass
ejection (CME) seen on the disk of the Sun. Observations with the EIT
and LASCO experiments on SOHO show that the CME starts in a small volume
and is associated with slow motions of prominence material. At about
the same time, a shock wave is created that travels out into the corona
at a velocity of 400 km s^{-1} ahead of an eruptive prominence. This
shock wave is clearly the event that is later seen as a classical CME
when observed in the coronagraph above 1.5 solar radii. Although the
CME clearly starts in a small region, a chain of activity near the
limb may also be associated with this event.
Title: Microwave and UV observations of filaments with SOHO and
the VLA
Authors: Alissandrakis, C. E.; Drago, F.; Bastian, T.; Bocchialini,
K.; Delaboudiniere, J. -P.; Lemaire, P.; Vial, J. -C.; Harrison,
R. A.; Thompson, B.
Bibcode: 1997ASPC..118..289A
Altcode: 1997fasp.conf..289A
Observations performed in coordination between SOHO instruments and
ground-based observatories offer the unique possibility to derive
information simultaneously in several wavelengths formed at different
altitudes and/or temperatures in the solar atmosphere. The SUMER and
CDS spectrometers, the imaging telescope EIT aboard SOHO, and the VLA
provide complementary information in the UV and the radio ranges. We
illustrate such a coordination with observations of filaments in the
transition region, performed in July 1996. The observations in the UV
between 10(4) and 10(6) K provide the differential emission measure
as a function of temperature; this can be used to compute the expected
brightness temperature in the microwave range and check models of the
filament-corona transition region.
Title: First Results from EIT
Authors: Clette, F.; Delaboudiniere, J. -P.; Artzner, G. E.; Brunaud,
J.; Gabriel, A. H.; Hochedez, J. -F.; Millier, F.; Song, X. Y.; Au, B.;
Dere, K. P.; Howard, R. A.; Kreplin, R.; Michels, D. J.; Moses, J. D.;
Defise, J. -M.; Jamar, C.; Rochus, P.; Chauvineau, J. -P.; Marioge,
J. -P.; Catura, R. C.; Lemen, J. R.; Shing, L.; Stern, R. A.; Gurman,
J. B.; Neupert, W. M.; Maucherat, A.; Cugnon, P.; van Dessel, E. L.
Bibcode: 1997ASPC..118..268C
Altcode: 1997fasp.conf..268C
The Extreme-UV Imaging telescope has already produced more than 15000
wide-field images of the corona and transition region, on the disk
and up to 1.5R_⊙ above the limb, with a pixel size of 2.6\arcsec. By
using four different emission lines, it provides the global temperature
distribution in the quiet corona, in the range 0.5 to 3*E(6) K. Its
excellent sensitivity and wide dynamic range allow unprecedented views
of low emission features, even inside coronal holes. Those so-called
``quiet'' regions actually display a wide range of dynamical phenomena,
in particular at small spatial scales and at time scales going down
to only a few seconds, as revealed by all EIT time sequences of
full- or partial-field images. The initial results presented here
demonstrate the importance of this wide-field imaging experiment for
a good coordination between SOHO and ground-based solar telescopes,
as well as for science planning.
Title: Coordinated SOHO Observations of Polar Plumes
Authors: Deforest, C. E.; Scherrer, P. H.; Tarbell, T.; Harrison,
R. A.; Fludra, A.; Delaboudiniere, J. P.; Gurman, J. B.; Wilhelm,
K.; Lemaire, P.; Hassler, D. M.; Kohl, J. L.; Noci, G.; Fineschi,
S.; Brueckner, G. E.; Howard, R. A.; Cyr, O. C. St.
Bibcode: 1996AAS...188.4909D
Altcode: 1996BAAS...28R.898D
On 7 and 8 March 1996, SOHO instruments engaged in their first
joint science operation, a 12-hr observation of polar plumes
over the South polar coronal hole. The observing mini-campaign
included observations from SOHO, other spacecraft, and ground-based
observatories. Contributing SOHO instruments -- in order of altitude,
MDI, CDS, SUMER, EIT, UVCS, and LASCO -- made overlapping, simultaneous
observations of plume structures from the photosphere out to the
LASCO C3 limit of 32 solar radii. MDI provided line-of-sight surface
magnetograms with a one-min cadence and 0.6 arcsec resolution;
CDS, SUMER, and EIT supplied temperature-sensitive images of the
lower corona with varying cadences and resolutions; UVCS measured
fluctuations in Ly B intensity across the coronal hole with a one-min
cadence at 1.4 R0; and LASCO imaged the entire corona out to 30 R0 in
various visible passbands. Plume footpoints in the lower corona are
observed by EIT and CDS to vary by a factor of two in EUV brightness
with a timescale of tens of minutes, while the structures above are
(as as been previously observed) quiescent on at least a ten-hr time
scale. We present preliminary results of cross-instrument analysis
of the observed plumes, and suggest how this and similar future data
sets can be used to constrain quiet-sun wind acceleration and coronal
heating models for the coronal hole. This research is supported by
the SOI-MDI NASA contract NAG5-3077 at Stanford University. SOHO is
project of international cooperation between NASA and ESA.
Title: Observations of the South coronal hole from EIT and YOHKOH
Authors: Handy, B. N.; Catura, R.; Freeland, S.; Lemen, J.; Stern,
R.; Gurman, J. B.; Delaboudiniere, J. P.; Artzner, G.; Gabriel, A.;
Maucherat, A.; Defise, J. M.; Jamar, C.; Rochus, P.; Clette, F.;
Cugnon, P.; Howard, R.; Michels, D.; Moses, J. D.; Dere, K.; Cyr,
O. C. St.; Catura, R.; Freeland, S.; Lemen, J.; Stern, R.; Neupert,
W.; Einfalt, E.; Newmark, J.
Bibcode: 1996AAS...188.0206H
Altcode: 1996BAAS...28..821H
The Extreme ultraviolet Imaging Telescope (EIT) on board the
SOHO spacecraft is capable of studying solar transition region,
chomospheric and coronal plasmas over bandpasses optimized for He II
304 Angstroms (0.08 MK), Fe IX/X 171, 173 Angstroms (0.8 - 1.0 MK),
Fe XII 195 Angstroms (1.5 MK), and Fe XV 284 Angstroms (2.0 - 2.5
MK) with 2.5 arcsecond spatial resolution. This telescope in concert
with the Yohkoh/SXT instrument allows us to simultaneously observe
solar structures at temperatures ranging from less than 0.1MK in the
transition region to over 3MK in the solar corona. EIT has had several
opportunities to observe the South coronal hole with high spatial and
temporal resolution. We compare observations from EIT and SXT with
an eye towards correlating temporal variations over the range of
wavelengths, activity of polar crown filament systems and relating
large-scale morphology of the X-ray corona to the transition region
in He II.
Title: There's No Such Thing as the Quiet Sun: EUV Movies from SOHO
Authors: Gurman, J. B.; Delaboudiniere, J. P.; Artzner, G.; Gabriel,
A.; Maucherat, A.; Defise, J. M.; Jamar, C.; Rochus, P.; Clette, F.;
Cugnon, P.; Howard, R.; Michels, D.; Moses, J. D.; Dere, K.; Cyr,
O. C. St.; Catura, R.; Freeland, S.; Lemen, J.; Stern, R.; Neupert,
W.; Einfalt, E.; Newmark, J.
Bibcode: 1996AAS...188.3718G
Altcode: 1996BAAS...28..880G
We present unique time series of high-resolution solar images from the
normal-incidence Extreme ultraviolet Imaging Telescope (EIT) on board
the SOHO spacecraft. With a pixel scale of 2.6 arc sec and a detector
dynamic range of > 10(4) , the EIT can be used to study the dynamics
of chromospheric and coronal features in multilayer bandpasses optimized
for He II 304 Angstroms (0.08 MK), Fe IX/X 171, 173 Angstroms (0.8 -
1.0 MK), Fe XII 195 Angstroms (1.5 MK), and Fe XV 284 Angstroms (2.0 -
2.5 MK). Among the most striking features of the digital movies we will
display are: the dynamic nature of small-scale loop features in the
polar coronal holes, the constant activity of the polar crown filament
systems, the locations of the bases of polar plumes, the presence
of dark (scattering) filament material in the coronal emission line
images, and the evolution of a unique, linear, dark feature in a young
active region. The latter feature is suggestive of the ``coronal void''
observed in the electron scattering corona by Macqueen et al./ (1983).
Title: Observations of the south coronal hole from EIT and Yohkoh.
Authors: Handy, B. N.; Catura, R.; Freeland, S.; Lemen, J.; Stern,
R.; Gurman, J. B.; Delaboudinière, J. P.; Artzner, G.; Gabriel,
A.; Maucherat, A.; Defise, J. M.; Jamar, C.; Rochus, P.; Clette, F.;
Cugnon, P.; Howard, R.; Michels, D.; Moses, J. D.; Dere, K.; St. Cyr,
O. C.; Neupert, W.; Einfalt, E.; Newmark, J.
Bibcode: 1996BAAS...28Q.821H
Altcode:
No abstract at ADS
Title: EIT Images of the EUV Solar Atmosphere
Authors: Portier-Fozzani, F.; Moses, J. D.; Delaboudiniere, J. P.;
Gurman, J. B.; Clette, F.; Maucherat, A.
Bibcode: 1996ASPC..111..402P
Altcode: 1997ASPC..111..402P
The Extreme-ultraviolet Imaging Telescope (EIT) was one of several
instruments launched on board SOHO on 1995 Dec 2. It has already
produced thousands of wide-field images of the low corona at 4
wavelengths (171, 195, 284 and 304 Å). These wavelengths correspond
to different emission lines, formed over a wide range of plasma
temperatures. The first EIT images and movies reveal how this sensitive
instrument will provide unprecedented information about the dynamics
of small scale phenomena in the quiet solar corona and inside coronal
holes. Results of a local deconvolution method, used to correct a grid
pattern present in raw EIT images, are also presented.
Title: EIT: Extreme-Ultraviolet Imaging Telescope for the SOHO Mission
Authors: Delaboudinière, J. -P.; Artzner, G. E.; Brunaud, J.; Gabriel,
A. H.; Hochedez, J. F.; Millier, F.; Song, X. Y.; Au, B.; Dere, K. P.;
Howard, R. A.; Kreplin, R.; Michels, D. J.; Moses, J. D.; Defise,
J. M.; Jamar, C.; Rochus, P.; Chauvineau, J. P.; Marioge, J. P.;
Catura, R. C.; Lemen, J. R.; Shing, L.; Stern, R. A.; Gurman, J. B.;
Neupert, W. M.; Maucherat, A.; Clette, F.; Cugnon, P.; Van Dessel,
E. L.
Bibcode: 1995SoPh..162..291D
Altcode:
The Extreme-ultraviolet Imaging Telescope (EIT) will provide wide-field
images of the corona and transition region on the solar disc and up to
1.5 R⊙ above the solar limb. Its normal incidence multilayer-coated
optics will select spectral emission lines from Fe IX (171 å), Fe
XII (195 å), Fe XV (284 å), and He II (304 å) to provide sensitive
temperature diagnostics in the range from 6 × 104 K to 3
× 106 K. The telescope has a 45 x 45 arcmin field of view
and 2.6 arcsec pixels which will provide approximately 5-arcsec spatial
resolution. The EIT will probe the coronal plasma on a global scale,
as well as the underlying cooler and turbulent atmosphere, providing
the basis for comparative analyses with observations from both the
ground and other SOHO instruments. This paper presents details of the
EIT instrumentation, its performance and operating modes.
Title: Calibration of the EIT instrument for the SOHO mission
Authors: Defise, Jean-Marc; Song, Xueyan Y.; Delaboudiniere,
Jean-Pierre; Artzner, Guy E.; Carabetian, Charles; Hochedez,
Jean-Francois E.; Brunaud, Jacqueline; Moses, John D.; Catura,
Richard C.; Clette, Frederic; Maucherat, Andre J.
Bibcode: 1995SPIE.2517...29D
Altcode:
Optical characteristics in the wavelength range 15 - 75 nm of the
EUV imaging telescope to be launched soon on the SOHO mission are
discussed. Bandpasses and photometric sensitivity of the multilayered
optics telescope have been measured by a dedicated synchrotron light
source at Orsay, France.
Title: EIT: The Extreme Ultraviolet Imaging Telescope. Synoptic
Observations of Small and Large-Scale Coronal Structures
Authors: Clette, F.; Delaboudinière, J. P.; Dere, K. P.; Cugnon,
P.; EIT Science Team
Bibcode: 1995LNP...444..251C
Altcode: 1995cmer.conf..251C
The EIT will provide wide-field images of the corona and transition
region, on the solar disc and up to 1 R⊙ above the
limb. Its normal incidence multilayer-coated optics will select the
spectral emission lines of four ions (Fe IX, 171 Å; Fe XII, 195
Å; Fe XV, 284 Å; Hell, 304 Å), providing a sensitive temperature
diagnostic in the range 6.104 to 3.106K. This
SOHO instrument will thus probe the coronal plasma on a global scale,
as well as the underlying cooler and turbulent atmosphere. The EIT's
characteristics and performances are presented, and prospects for
coordinated observations with ground-based radio observatories are
outlined.
Title: EUVITA — An extreme UV imaging telescope array with spectral
capability
Authors: Courvoisier, T. J. -L.; Orr, A.; Bühler, P.; Zchnder,
A.; Henneck, R.; Stauffacher, F.; Biakhowski, J.; Schlumpf, N.;
Schoeps, W.; McHedlishvili, A.; Sunyaev, R.; Arefev, V.; Yascovich,
A.; Babalyan, G.; Pavlinsky, M.; Delaboudinière, J. P.; Carone, T.;
Siegmund, O.; Warren, J.; Leahy, D.; Salaschenko, N.; Platonov, J.
Bibcode: 1993AdSpR..13l.299C
Altcode: 1993AdSpR..13..299C
EUVITA is a set of 8 extreme UV normal incidence imaging telescopes,
each of them sensitive in a narrow band (λ/Δλ = 15 to 80), centered
at wavelengths between 50 and 175Å. Each telescope has an effective
area of a few cm2; a field of view of 1.2° and a spatial
resolution of 10 arcsec.EUVITA will be flown on the Russian mission
SPECTRUM X-G. This satellite will be launched in a highly eccentric
orbit with a period of 4 days, allowing long, uninterrupted observations
(e.g. 105 seconds). EUVITA's narrow spectral bands allow
the measurement of source parameters such as temperature or power law
index as well as interstellar absorption, and will resolve groups of
strong lines emitted by optically thin hot plasmas.
Title: Performance of back-illuminated Tektronix CCDs in the extreme
ultraviolet
Authors: Moses, John D.; Howard, Russell A.; Wang, Dennis; Catura,
Richard C.; Lemen, J. R.; Shing, Lawrence; Stern, Robert A.; Hochedez,
Jean-Francois E.; Delaboudiniere, Jean-Pierre
Bibcode: 1993SPIE.2006..252M
Altcode:
The quantum efficiency (QE) and flat field characteristics of
back-illuminated 1024 X 1024 Tektronix CCDs have been measured in the
extreme ultraviolet (EUV) between 44 and 1216 angstroms. These CCDs have
been fabricated for the focal plane detector of the Extreme-ultraviolet
Imaging Telescope (EIT) on the Solar and Heliospheric Observing
spacecraft. The back-side surface of the EIT CCDs have been specially
processed to enhance and stabilize the EUV QE. All requirements for
QE are met by these devices, although a poorly understood variation
of QE with temperature will complicate data analysis.
Title: EUVITA - an extreme UV imaging telescope array with spectral
capability
Authors: Courvoisier, J. -L.; Orr, A.; Bühler, P.; Zehnder, A.;
Henneck, R.; Stauffacher, F.; Biakhowski, J.; Schlumpf, N.; Schoeps,
W.; McHedlishvili, A.; Sunyaev, R.; Aref'ev, V.; Yascovich, A.;
Babalyan, G.; Pavlinsky, M.; Delaboudinière, J. P.; Carone, T.;
Siegmund, 0.; Warren, J.; Leahy, D.; Salaschenko, N.; Platonov, J.
Bibcode: 1993ExA.....4..117C
Altcode:
EUVITA is a set of 8 extreme UV and soft X-ray normal incidence imaging
telescopes, each of them sensitive in a narrow band (λ/Δλ=15 to
80), centered at wavelengths between 50 and 175 Å. Each telescope
has an effective area of a few cm2, a field of view of
1.2° and an angular resolution of 10 arcseconds. EUVITA will be Sown
on the Russian mission SPECTRUM X-G. This satellite will be launched
in a highly eccentric orbit with a period of 4 days, allowing long,
uninterrupted observations (e.g. 105 seconds). The present
paper includes an overview of EUVITA's scientific capabilities and a
short description of the instrument. Simulations of various types of
sources show EUVITA's capability to detect galactic and extragalactic
EUV sources. EUVITA's narrow spectral bands allow the measurement
of source parameters such as temperature or power law index as well
as interstellar absorption, and will resolve groups of strong lines
emitted by optically thin hot plasmas.
Title: Tuning multilayered mirror light traps for rejection of
30.4-nm radiation
Authors: Delaboudiniere, Jean-Pierre; Hochedez, Jean-Francois;
Chauvineau, Jean-Pierre; Valiergue, Laurence
Bibcode: 1993SPIE.1742..296D
Altcode:
Very efficient mirrors designed for rejection of the 30.4 nm HeII line
while transmitting the 28.4 nm FeXV line are needed for observations
of the solar corona. Light traps, based on multilayered structures,
using moderately absorbing diffractor layers of SiO2 and aluminum
as spacer material, have been successfully fabricated providing
dramatically high rejection ratios. However, accurate tuning at the
desired wavelength has proven to be extremely difficult to achieve in
combination with high nominal reflectivity. Very slight deviations
of thicknesses or optical constants can easily destroy the desired
antiresonance effect. Classical Mo/Si structures, although somewhat
less selective, can also be specially designed for this application
and they prove more amenable to proper adjustment.
Title: Solar corona synoptic observations from SOHO with an Extreme
Ultraviolet Imaging Telescope.
Authors: Delaboudinière, J. P.; Gabriel, A. H.; Artzner, G. E.;
Dere, K.; Howard, R.; Michels, D.; Catura, R.; Lemen, J.; Stern, R.;
Gurman, J.; Neupert, W.; Cugnon, P.; Koeckelenbergh, A.; van Dessel,
E. L.; Jamar, C.; Maucherat, A.
Bibcode: 1992ESASP.348...21D
Altcode: 1992cscl.work...21D
The major scientific objective of the EUV Imaging Telescope (EIT)
is to study the evolution of coronal structure over a wide range
of spatial and temporal scales and temperatures. A second strategic
objective is to provide full disk synoptic maps of the global corona
to aid in unifying SOHO (Solar and Heliospheric Observatory)/Cluster
investigations. EIT will also provide images to support the planning
of detailed spectroscopic investigations by the CDS (Coronal Diagnostic
Spectrometer) and SUMER spectrometers in SOHO. EIT observations will be
made in four narrow spectral bands, centered at 171 A (Fe 9), 195 A(Fe
12), 284 A (Fe 15), and 304 A (He 2) representing restricted temperature
domains within a wide temperature range from 40,000 to 3,000,000
K. The results will be images of the solar atmosphere from the upper
chromosphere and transition region to the active region corona. These
maps, made at appropriate time intervals, will be used to study the fine
structures in the solar corona and to relate their dynamic properties
to the underlying chromosphere and photosphere. Dynamic events in the
inner corona will be related to white light transients in the outer
corona, and observations of the internal structure of coronal holes
will be used to investigate origins of the solar wind.
Title: The helioseismology experiment on the Phobos planetary
mission. Preliminary results
Authors: Frohlich, C.; Bonnet, R. M.; Bruns, A. V.; Vial, J. C.;
Delaboudiniere, J. P.; Domingo, V.; Kollath, Z.; Kotov, V. A.;
Rachkovskii, D. N.; Wehrli, Ch.; Toulain, T.; Shumko, S. M.
Bibcode: 1991BCrAO..83...18F
Altcode:
No abstract at ADS
Title: The helioseismological experiment at the Phobos interplanetary
station - Preliminary results
Authors: Froehlich, C.; Bonnet, R. M.; Bruns, A. V.; Vial, J. C.;
Delaboudiniere, J. P.; Domingo, V.; Kollath, Z.; Kotov, V. A.;
Rachkovskii, D. N.; Wehrli, Ch.
Bibcode: 1991IzKry..83...22F
Altcode:
Preliminary results obtained from IPHIR (Interplanetary Helioseismology
by Irradiance Measurements), a solar irradiance experiment on board
the Soviet planetary mission Phobos-2, are presented. During the
spacecraft's flight to Mars, the instrument gathered valuable data on
tiny variations of solar irradiance over the course of six months. The
data clearly show 5-min oscillations with relative amplitudes of about
10 exp -5 and with a well-defined pattern of discrete peaks in the
power spectrum. The data of the red channel (it exhibited the lowest
degradation of sensitivity over time) reveal remarkable temporal changes
of amplitudes of discrete peaks within a period range of about 5 min,
but with excellent frequency stability.
Title: Use of thinned backside illuminated CCD from the extreme
ultraviolet to the soft ultraviolet
Authors: Hochedez, Jean-Francois E.; Lemaire, Philippe; Delaboudiniere,
Jean-Pierre; Cougrand, Bernard; Barba, Julien
Bibcode: 1989SPIE.1070...53H
Altcode:
No abstract at ADS
Title: Extreme ultraviolet imaging telescope on board the Solar
Heliospheric Observatory
Authors: Delaboudiniere, Jean-Pierre; Gabriel, Alan H.; Artzner,
Guy E.; Millier, F.; Michels, Donald J.; Dere, Kenneth P.; Howard,
Russell A.; Kreplin, Robert W.; Catura, Richard C.; Stern, Robert A.;
Lemen, James R.; Neupert, Werner M.; Gurman, Joseph B.; Cugnon, P.;
Koeckelenbergh, A.; van Dessel, E. L.; Jamar, Claude A.; Maucherat,
Andre J.; Chauvineau, Jean-Pierre; Marioge, Jean-Paul
Bibcode: 1989SPIE.1160..518D
Altcode: 1989xeoa.conf..518D
The design of the multibandpass Extreme-Ultraviolet Imaging Telescope
designed for 1996 launch on board the Solar Heliospheric Observatory
is described. The telescope will observe simultaneously distinct
temperature ranges in the solar corona, defined by well chosen emission
lines. Images in four narrow bandpasses at wavelengths ranging from 17
to 31 nm will be obtained using normal-incidence multilayered optics
deposited on quadrants of a Ritchey-Chretien telescope. Results are
presented on the performances measured on a 2/3 scale mock-up. The
bandpasses could be adjusted to better than 1 percent in wavelength.
Title: Metal oxide multilayers with narrow band-passes.
Authors: Delaboudiniere, J. P.; Vien, T. K.; Chauvineau, J. P.
Bibcode: 1989SPIE.1160..260D
Altcode: 1989xeoa.conf..260D
Metal oxide multilayers provide reflecting coatings in the 15 - 50
nm range with exceptionnal properties. The authors discuss filters
featuring narrow band-passes and/or very sharp cut-offs. Possible
effects of degraded manufacturing processes are also evaluated.
Title: IPHIR: The helioseismology experiment on the PHOBOS mission.
Authors: Fröhlich, C.; Bonnet, R. M.; Bruns, A. V.; Delaboudinière,
J. P.; Domingo, V.; Kotov, V. A.; Kollath, Z.; Rashkovsky, D. N.;
Toutain, T.; Vial, J. C.; Wehrli, C.
Bibcode: 1988ESASP.286..359F
Altcode: 1988ssls.rept..359F
IPHIR (InterPlanetary Helioseismology by IRradiance measurements) is
a solar irradiance experiment on the USSR planetary mission PHOBOS to
Mars and its satellite Phobos. The experiment is a cooperative effort
of PMOD/WRC, LPSP, SSD/ESA, KrAO and CRIP. The sensor is a three channel
sunphotometer (SPM) which measures the solar spectral irradiance at 335,
500 and 865 nm with a precision of better than 1 ppm. A two axis solar
sensor (TASS) is added to monitor the moderate solar pointing of the
spacecraft. A microprocessor based data processing unit controls the
sensor operation, acquires the data, and performs the data compression
for the transmission at a mean rate of 1 bit/s. The two spacecrafts
have been launched on July 7th and 12th, 1988. The experiment on
PHOBOS I gathered data during 45 days before the S/C was lost, the
one on PHOBOS II is still operating. The data recovery is excellent
with virtually 100% coverage. Although the signal is disturbed by the
pointing of the spacecraft the results of a preliminary analysis in
the range of the 5-minutes oscillations demonstrate the improvement
achievable due to the fact that the time series is truly continuous
and the instrumental and sampling noise is very low.
Title: EIT: Solar corona synoptic observations from SOHO with an
Extreme-ultraviolet Imaging Telescope
Authors: Delaboudiniere, J. P.; Gabriel, A. H.; Artzner, G. E.;
Michels, D. J.; Dere, K. P.; Howard, R. A.; Catura, R.; Stern, R.;
Lemen, J.; Neupert, W.
Bibcode: 1988sohi.rept...43D
Altcode:
The Extreme-ultraviolet Imaging Telescope (EIT) of SOHO (solar and
heliospheric observatory) will provide full disk images in emission
lines formed at temperatures that map solar structures ranging from
the chromospheric network to the hot magnetically confined plasma in
the corona. Images in four narrow bandpasses will be obtained using
normal incidence multilayered optics deposited on quadrants of a
Ritchey-Chretien telescope. The EIT is capable of providing a uniform
one arc second resolution over its entire 50 by 50 arc min field of
view. Data from the EIT will be extremely valuable for identifying
and interpreting the spatial and temperature fine structures of the
solar atmosphere. Temporal analysis will provide information on the
stability of these structures and identify dynamical processes. EIT
images, issued daily, will provide the global corona context for aid
in unifying the investigations and in forming the observing plans for
SOHO coronal instruments.
Title: Progress with LSM optics for solar observations within the
French space program.
Authors: Delaboudiniere, J. P.
Bibcode: 1987RALR...43..133D
Altcode:
Development of Layered Synthetic Microstructures for XUV optics has
begun a few years ago in several French laboratories. The author's
laboratory has been concerned with potential applications of this new
technique to observations of the solar corona in the EUV wavelength
range with normal incidence optical systems. This activity was recently
bolstered by perspectives opened by the projected ESA solar mission
SOHO.
Title: Space qualification of multilayered optics.
Authors: Delaboudiniere, J. -P.; Chauvineau, J. -P.; Marioge, J. -P.
Bibcode: 1985SPIE..563...44D
Altcode:
The feasibility for the ESA SOHO mission, of spectrally selected normal
incidence telescopes in the XUV wavelength range is demonstrated in
an evaluation of multilayered mirrors illuminated by the sun. Worst
case solar vacuum tests of unprotected telescopes illuminated by
a xenon arc lamp simulator indicate less than 10 percent decrease
in reflectivity of the exposed section of the Hf/Si sample for the
secondary mirrors. Primary mirror tests are currently being performed
aboard the NASA Long Duration Exposure Facility. Results of protecting
filter tests suggest a growth from 40-100 A in the thickness of the
two aluminum oxide layers protecting the aluminum, in contradiction
to previous findings (Hunter et al., 1973).
Title: Aspherization and multilayer coating of a Ritchey-Chrétien
telescope for λ = 30.4 nm.
Authors: Chauvineau, J. P.; Decanini, D.; Mullot, M.; Valiergue, L.;
Delaboudiniere, J. P.
Bibcode: 1985SPIE..563..275C
Altcode:
A high vaccum system designed for the deposition of multilayers for
soft X-ray mirrors is described. It is applied to the aspherization
and multilayer coating of the mirrors of a solar Ritchey-Chretien
telescope. In a first step, laterally graded boron layers are
deposited on flat polished silica substrate in order to determine
their thickness profile by visible light interferometry. The next step
consists in the characterization of multilayers deposited on top of the
boron layer. Grazing incidence X-ray interferometry is applied to the
measurement of interface roughness; the results are used to predict the
performances of W/Si multilayers; it is found that reflectivity values
of about 25 percent could be obtained for normal reflection at 30.4 nm.
Title: Compact resonance absorption spectrometer to monitor the
profile of the solar He 58.4 nanometer line
Authors: Crifo, J. F.; Seidl, P.; Delaboudinière, J. P.; Schmidtke, G.
Bibcode: 1980RScI...51..321C
Altcode:
A miniature resonance absorption spectrometer is able to perform a
routine monitoring in space of the line profile and intensity of the
He i resonance line from the solar disk with a time resolution of about
1 min and a spectral resolution of 105. It consists of a predispersive
spectrometer incorporating a helium gas absorption cell. The instrument
has been designed to meet a small size and weight. It was tested on a
rocket flight in June 1976. The construction, principles of operation,
and laboratory calibration of the instrument are presented. Its
capability to resolve details of the order of 0.3 pm FWHM and its
sensitivity to the intensity of line wings three order of magnitudes
fainter than the peak of the line have been established by laboratory
investigation.
Title: Multiple scattering effects in a cylindrical helium absorption
cell operating close to the resonance line at lambda 584 Å.
Authors: Delaboudiniere, J. P.
Bibcode: 1979JQSRT..22..411D
Altcode:
The departure from Beer's law due to multiple scattering in a helium
absorption cell is investigated. A complete description of the relevant
scattering mechanisms, within the frame of a Monte Carlo simulation,
is used to evaluate the effects of polarization, collisional line
broadening and frequency redistribution. A cylindrical geometry is
studied which includes optical reflection effects at the boundaries
of the enclosure.
Title: Intercomparison/compilation of relevant solar flux data
related to aeronomy/Solar Cycle 20/
Authors: Delaboudiniere, J. P.; Donnelly, R. F.; Hinteregger, H. E.;
Schmidtke, G.; Simon, P. C.
Bibcode: 1978cosp.conf.....D
Altcode:
The intercomparison of solar irradiance (in the UV/XUV spectra)
is presented graphically for Solar Cycle 20. The smoothed sunspot
number is chosen over the more fluctuating F sub 10.7 radio flux to
demonstrate solar activity. Attention is given to variations in solar
irradiance in terms of duration, i.e., short-, medium-, and long-term.
Title: Possible contribution of radiation from the 2s2p
42P level of O II in dayglow measurements of
the He I line at 584 Å
Authors: Delaboudiniere, J. P.
Bibcode: 1977P&SS...25..193D
Altcode:
Intensity of dayglow emmisions in the lines of 0 II at 537 and 581
Å is evaluated from presently accepted atomic parameters, EUV solar
fluxes and atmospheric models. An improvement of the experimental
techniques used up to now is suggested to identify these emissions
and provide new data on ionospheric processes.
Title: Preliminary results obtained from the solar EUV experiment
on board the D2B Aura satellite.
Authors: Delaboudiniere, J. P.; Millier, F.
Bibcode: 1977spre.conf..519D
Altcode: 1977spre.proc..519D
The solar EUV experiment on board D2B has been operating successfully
since November 1, 1975. Three main sets of data are being gathered:
(1) spectroheliograms at a resolution of one arcmin within prominent
solar lines formed at temperatures between 20,000 and 3 million K,
providing detailed observations of individual active regions; (2)
disk-integrated values of the solar flux in the range 17-127 nm at a
resolution of 0.8 to 0.6 nm suitable for defining the spectral energy
input to the upper atmosphere; and (3) simultaneous measurements of
solar extinction at sunset and sunrise at eight different wavelengths,
providing a partially redundant set of information for remote sounding
of atmospheric composition and temperature between 100 and 400 km.
Title: The profile of the helium I 584 Å solar line. Preliminary
results from rocket-borne resonance absorption spectrometer.
Authors: Delaboudiniere, J. P.; Crifo, J. F.
Bibcode: 1976spre.conf..803D
Altcode: 1976spre.proc..803D
A measurement of the line profile of the He I 584 A line from the
sun has been made on board a rocket on 20 January 1975. Wavelength
resolution is obtained by the resonance absorption method. The
instrument is described, and its performance in flight is analysed. The
principles of data reduction are given, and preliminary results are
presented and compared with available data from other sources. The width
of the solar He I resonance line is found to be larger than 110 mA.
Title: A rocket borne absorption cell for high resolution spectroscopy
of the He I line at 584 Å.
Authors: Delaboudiniere, J. P.; Carabetian, C.
Bibcode: 1975SSI.....1...91D
Altcode:
A rocket instrument designed to measure the profile of the 584 A line
of helium emitted by the sun, has been constructed. The most original
part of this instrument is a resonant absorption cell for use in the
extreme ultraviolet. Filled with rare gases such a device allows the
spectral analysis of a wide range of line shapes because a very high
optical thickness can be reached. The flexibility of the absorption
cell method has been demonstrated both by numerical analysis and by
laboratory experiment. Although the planned experiment has not been
successful yet, it has been proven that absorption cells, can be used
for space applications and several have been tested successfully in
flight on board rockets.