explanation blue bibcodes open ADS page with paths to full text
Author name code: huber
ADS astronomy entries on 2022-09-14
=author:"Huber, M.C.E." OR =author:"Huber, Martin C.E."
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Title: Spectroradiometry with space telescopes
Authors: Pauluhn, Anuschka; Huber, Martin C. E.; Smith, Peter L.;
Colina, Luis
2015A&ARv..24....3P Altcode: 2015arXiv151108686P; 2016A&ARv..24....3P
Radiometry, i.e. measuring the power of electromagnetic
radiation—hitherto often referred to as "photometry"—is of
fundamental importance in astronomy. We provide an overview of how
to achieve a valid laboratory calibration of space telescopes and
discuss ways to reliably extend this calibration to the spectroscopic
telescope's performance in space. A lot of effort has been, and still
is going into radiometric "calibration" of telescopes once they are in
space; these methods use celestial primary and transfer standards and
are based in part on stellar models. The history of the calibration
of the Hubble Space Telescope serves as a platform to review these
methods. However, we insist that a true calibration of spectroscopic
space telescopes must directly be based on and traceable to laboratory
standards, and thus be independent of the observations. This has
recently become a well-supported aim, following the discovery of the
acceleration of the cosmic expansion by use of type-Ia supernovae,
and has led to plans for launching calibration rockets for the visible
and infrared spectral range. This is timely, too, because an adequate
exploitation of data from present space missions, such as Gaia, and
from many current astronomical projects like Euclid and WFIRST demands
higher radiometric accuracy than is generally available today. A survey
of the calibration of instruments observing from the X-ray to the
infrared spectral domains that include instrument- or mission-specific
estimates of radiometric accuracies rounds off this review.
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Title: Observing Photons in Space: A Guide to Experimental Astronomy
Authors: Huber, M. C. E.; Pauluhn, A.; Culhane, J. L.; Timothy, J. G.;
Wilhelm, K.; Zehnder, A.
2013opsg.book.....H Altcode:
No abstract at ADS
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Title: Observing Photons in Space: A Guide to Experimental Spae
Astronomy
Authors: Huber, M. C. E.; Pauluhn, A.; Culhane, J. L.; Timothy, J. G.;
Wilhelm, K.; Zehnder, A.
2013ops..book.....H Altcode:
No abstract at ADS
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Title: The Role of Harvard College Observatory and UVCS in the
Development of SOHO
Authors: Huber, M. C. E.
2010ASPC..428...15H Altcode:
No abstract at ADS
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Title: Introduction
Authors: Huber, Martin C. E.; Treumann, Rudolf A.
2010png..book....1H Altcode:
No abstract at ADS
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Title: Observing Photons in Space
Authors: Huber, Martin C. E.; Pauluhn, Anuschka; Timothy, J. Gethyn
2010ISSIR...9....3H Altcode:
This first chapter of the book "Observing Photons in Space" serves to
illustrate the rewards of observing photons in space, to state our
aims, and to introduce the structure and the conventions used. The
title of the book reflects the history of space astronomy: it started
at the high-energy end of the electromagnetic spectrum, where the
photon aspect of the radiation dominates. Nevertheless, both the
wave and the photon aspects of this radiation will be considered
extensively. In this first chapter we describe the arduous efforts
that were needed before observations from pointed, stable platforms,
lifted by rocket above the Earth"s atmosphere, became the matter
of course they seem to be today. This exemplifies the direct link
between technical effort -- including proper design, construction,
testing and calibration -- and some of the early fundamental insights
gained from space observations. We further report in some detail the
pioneering work of the early space astronomers, who started with the
study of γ- and X-rays as well as ultraviolet photons. We also show
how efforts to observe from space platforms in the visible, infrared,
sub-millimetre and microwave domains developed and led to today"s
emphasis on observations at long wavelengths.
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Title: Probing The Nature of Gravity
Authors: Everitt, C. W. F.; Huber, M. C. E.; Kallenbach, R.; Schäfer,
G.; Schutz, B. F.; Treumann, R. A.
2010png..book.....E Altcode:
No abstract at ADS
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Title: Calibration
Authors: Huber, Martin C. E.; Pauluhn, Anuschka; Timothy, J. Gethyn;
Zehnder, Alex
2010ISSIR...9..536H Altcode:
Calibrating instruments for photon observations in space involves a
number of parameters, most basic among them the pointing accuracy and
stability. Wavelength accuracy is important as well. A particularly
demanding and complex set of parameters to be determined concerns
the responsivity (sometimes also referred to as effective area or
detection efficiency) of the telescope-spectrometer combination. The
responsivity is a function of wavelength, and for its determination
the full set of geometric and spectro-optical properties of the
system needs to be quantified. High photon arrival rates may also
lead to nonlinearities that have to be assessed. A realistic physical
and chemical description of an astronomical object, i.e., the goal
of astrophysics, can only be reached with spectroradiometrically
calibrated telescopes and spectrometers. We stress that there is no a
priori celestial standard. A radiometric calibration must thus assure
that observed spectral irradiances (or radiances) are measured in
the units of the systeme International, which in turn are defined by
radiometric standards realised on Earth.
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Title: Postscript
Authors: Huber, Martin C. E.; Pauluhn, Anuschka; Culhane, J. Len;
Timothy, J. Gethyn; Wilhelm, Klaus; Zehnder, Alex
2010ISSIR...9..647H Altcode:
We summarise the aim and content of the book "Observing Photons in
Space" (ISSI SR-009), comment on emerging national space activities
around the globe, and point out the trends toward global collaborations
in space astronomy.
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Title: Introduction
Authors: Huber, Martin C. E.; Treumann, Rudolf A.
2009SSRv..148....1H Altcode: 2010SSRv..tmp...19H
No abstract at ADS
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Title: Lessons from Introducing New Scientific Disciplines Into
European Space Research
Authors: Huber, Martin C. E.
2009fqcf.book...91H Altcode:
Physics experiments in space will permit us to investigate natural
phenomena that cannot be observed on the ground, such as low-frequency
gravitational waves, and to reach uncharted realms of accuracy —
accessible only through experiments carried out in space — where
current foundations of physics can be further tested and potentially
falsified. Such projects require technologies that have not been in hand
for a long time but are available now. To avoid conflict of interest,
the merit of space projects in physics, from the proposal stage through
development, ought to be judged by experts in physics, rather than by
space scientists from other fields. It is time now to set aside some
funding to let missions in fundamental physics compete fairly with the
established space sciences, thereby enriching and deepening the space
enterprise — and broadening its advocacy base. We look, in the context
of the European space scene, at the measures and events that resurrected
the initially suppressed planetary sciences and brought solar physics
to blooming after a long drought; and derive ideas on how to increase
the number of flight opportunities for fundamental physics in space.
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Title: Lessons from Introducing New Scientific Disciplines Into
European Space Research
Authors: Huber, Martin C. E.
2007IJMPD..16.1967H Altcode:
Physics experiments in space will permit us to investigate natural
phenomena that cannot be observed on the ground, such as low-frequency
gravitational waves, and to reach uncharted realms of accuracy —
accessible only through experiments carried out in space — where
current foundations of physics can be further tested and potentially
falsified. Such projects require technologies that have not been in
hand for a long time but are available now. <P />To avoid conflict of
interest, the merit of space projects in physics, from the proposal
stage through development, ought to be judged by experts in physics,
rather than by space scientists from other fields. It is time now
to set aside some funding to let missions in fundamental physics
compete fairly with the established space sciences, thereby enriching
and deepening the space enterprise — and broadening its advocacy
base. <P />We look, in the context of the European space scene, at the
measures and events that resurrected the initially suppressed planetary
sciences and brought solar physics to blooming after a long drought;
and derive ideas on how to increase the number of flight opportunities
for fundamental physics in space.
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Title: Introduction (3)
Authors: Huber, M. C. E.
2006ESASP.637E...4H Altcode: 2006ESASP.637....4H; 2006bept.confE...4H
No abstract at ADS
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Title: SOHO in Venice
Authors: Huber, M. C. E.
2006ESASP.617E..31H Altcode: 2006soho...17E..31H
No abstract at ADS
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Title: Opening remarks (Solar variability: from core to outer
frontiers)
Authors: Huber, Martin C. E.
2002ESASP.506D..23H Altcode: 2002ESPM...10...23H; 2002svco.confD..23H
No abstract at ADS
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Title: A Delayed but Ultimately Successful Return
Authors: Huber, Martin C. E.
2002ESASP1261..109H Altcode: 2002ses..book..109H
No abstract at ADS
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Title: The scientific achievements of Klaus Wilhelm
Authors: Huber, Martin C. E.
2002ESASP.508..543H Altcode: 2002soho...11..543H
We summarise and illustrate the scientific achievements of Klaus
Wilhelm, starting with his diploma thesis. We also touch on his
science-policy work, which he did, first, as a staff member of ESRO
and, later on, as a representative of the scientific community in
ESA's Solar System Working Group. We then turn to Klaus Wilhelm's
influence and impact as the Principal Investigator (PI) of the SUMER
(Solar Ultraviolet Measurement of Emitted Radiation) experiment on
the Solar and Heliospheric Observatory, SOHO. As a distinguished
collaborator of the PI in an earlier groundbreaking space experiment,
namely the Halley Multicolour Camera (HMC) on ESA's Giotto probe, he
was predestined to become a leading figure in the SOHO Science Working
Team (SWT). The organisation of his experiment team was impeccable
and he always focused his mind on the scientific and technical aims of
SUMER. Personal or political issues never distracted him. Klaus Wilhelm
was instrumental in achieving a reliable radiometric calibration that
was traceable to a primary radiative laboratory standard. SUMER was
the UV experiment on SOHO with the best, most comprehensive laboratory
calibration and, thanks to integrity of design and a careful choice of
materials, SUMER had a remarkably stable responsivity in orbit. Thus,
Klaus Wilhelm as SUMER PI, had a decisive influence on two of the most
important improvements in vacuum-ultraviolet solar spectroscopy that
came with SOHO: cleanliness - in particular, with respect to condensable
matter - and radiometric accuracy. Klaus Wilhelm is a scientist with
sound principles. His enthusiasm, his pleasant personality, his urge
to rapidly and thoroughly resolve problems when they arise and his
continuous search for knowledge have led to the success of SOHO's
SUMER experiment, and of this career as a scientist.
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Title: Intercalibration of CDS and SUMER
Authors: Pauluhn, A.; Lang, J.; Schühle, U.; Solanki, S. K.; Wilhelm,
K.; Pike, C. D.; Thompson, W. T.; Rüedi, I.; Hollandt, J.; Huber,
M. C. E.
2002ESASP.508..223P Altcode: 2002soho...11..223P
The outcome of the Joint Observing Programme (JOP) Intercal-01, which
is the intercalibration of the SUMER (Solar Ultraviolet Measurements
of Emitted Radiation) instrument (detectors A and B) and the two CDS
(Coronal Diagnostic Spectrometer) instruments, the Normal Incidence
Spectrometer (NIS) and the Grazing Incidence Spectrometer (GIS),
is presented. Recent calibration updates of both instruments have
been employed, and the results indicate a very good correlation and
agreement of the measured radiances within the individual uncertainties.
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Title: The radiometric calibration and intercalibration of SOHO
Authors: Huber, M. C. E.; Pauluhn, A.; von Steiger, R.
2002ESASP.508..213H Altcode: 2002soho...11..213H
The radiometric calibration of spectrometric telescopes assures that
the observed spectral radiance (or irradiance) is measured on a scale
that is defined by the radiometric standards realised and used in
terrestrial laboratories. All SOHO instruments therefore have been
calibrated by use of source and detector standards that are traceable to
the primary radiometric standards. As any calibration, the laboratory
calibration has uncertainties. Moreover, environmental influences,
namely molecular and particulate contamination on the ground and effects
by photon and particle radiaton in space, do change the responsivity
of the instruments. In two workshops held at the International Space
Science Institute in Bern the individual instrument calibrations were
discussed and reconciled. The outcome of the workshops, to which
all instrument groups contributed, is summarised in a book that is
presented here before it goes to press.
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Title: Foreword
Authors: Pauluhn, A.; Huber, M. C. E.; von Steiger, R.
2002ISSIR...2D...7P Altcode: 2002ESASR...2D...7P; 2002rcs..confD...7P
No abstract at ADS
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Title: The Radiometric Calibration of SOHO
Authors: Pauluhn, A.; Huber, M. C. E.; von Steiger, R.
2002ISSIR...2.....P Altcode: 2002ESASR...2.....P; 2002rcs..conf.....P
No abstract at ADS
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Title: Solar Vacuum-ultraviolet Radiometry with SUMER
Authors: Wilhelm, K.; Schuhle, U.; Curdt, W.; Dammasch, I. E.;
Hollandt, J.; Lemaire, P.; Huber, M. C. E.
2002ISSIR...2..145W Altcode: 2002ESASR...2..145W; 2002rcs..conf..145W
Since the beginning of 1996, the space-based telescope and
spectrograph SUMER (Solar Ultraviolet Measurements of Emitted
Radiation) on the SOlar and Heliospheric Observatory (SOHO) of ESA
and NASA has obtained spectra of many features of the quiescent and
active Sun with high spectral and spatial resolution. In addition,
irradiance and radiance measurements of line and continuum emission
have been performed in the wavelength range 46.5 nm to 161.0 nm. The
instrument was radiometrically calibrated against the Berlin Electron
Storage ring for SYnchrotron radiation (BESSY I), a primary source
standard, with the help of a transfer source standard based on a
hollow-cathode discharge lamp. A thorough cleanliness programme,
specifically aimed at chemical contamination control, resulted in an
excellent radiometric stability of the normal-incidence optical system
as well as of the detectors. This has been verified under operational
conditions by various techniques employed during the SOHO mission,
such as line-ratio studies, observations of stars, and comparisons with
other instruments. The observations provide vacuum-ultraviolet (VUV)
radiometry of the Sun in many emission lines and continua of atoms
and ions with relative standard uncertainties of 15 % (detector A)
and 20 % (detector B) for the wavelength range 53 nm to 124 nm, with
larger uncertainties outside this interval and after the SOHO recovery
in 1998. We report on the present state of the SUMER radiometric
calibration and provide a full bibliography related to this topic.
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Title: The Century of Space Science, Volume I
Authors: Bleeker, Johan A.; Geiss, Johannes; Huber, Martin C. E.
2002css1.book.....B Altcode:
No abstract at ADS
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Title: Foreword
Authors: Pauluhn, A.; Huber, M. C. E.; von Steiger, R.
2002ISSIR...2D...5P Altcode: 2002ESASR...2D...5P; 2002rcs..confD...5P
No abstract at ADS
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Title: Spectroradiometry for Solar Physics in Space
Authors: Smith, P. L.; Huber, M. C. E.
2002ISSIR...2...21S Altcode: 2002rcs..conf...21S; 2002ESASR...2...21S
Realistic physical and chemical descriptions of the Sun require
observations that have been made with spectroradiometrically calibrated
telescopes and spectrometers, i.e., with instruments that have a
known spectral responsivity. Such calibrations assure that a measured
spectral radiance or irradiance is determined on a scale that is defined
by the radiometric standards realised and used in laboratories. For
ground-based observations of the Sun in the visible or near-infrared
spectral regions, comparisons with laboratory standards of radiance
or irradiance are relatively straightforward. However, measurements
at shorter or longer wavelengths, or measurements of the total solar
irradiance with a radiometric accuracy to within one part in 1000 which
is indispensable for climatology today, require observations outside the
atmosphere. For these the spectral responsivity of the instrumentation
must be known. However, calibrating telescope-spectrometer combinations
for the wide wavelength range of space observations is a complex and
problematic task, particularly for extended space missions. Satellite
telescope-spectrometer combinations can be calibrated before launch
in the laboratory by use of appropriate primary or secondary source
or detector standards. We review such standards and their use in the
context of the SOHO instrument calibrations and we note limitations in
accuracy and coverage of parameter space. Environmental influences,
such as contamination on the ground and the influence of radiation
in space, may, however, cause the spectral responsivity of satellite
instruments to change between laboratory calibration and initial
operation in space and during the subsequent long period of orbital
operations. In-orbit monitoring and validation of the responsivity
of a satellite instrument is, therefore, necessary. This has been
achieved for SOHO by intercomparisons of the responses of the various
instruments when a common source is viewed, by observations of stars
and by under-flights. In the past, solar physics has often broken
new ground and introduced and refined astronomical techniques. The
efforts to calibrate solar observations as they are reported in this
book should, therefore, be of interest for astronomy as a whole.
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Title: Intercalibration of CDS and SUMER
Authors: Pauluhn, A.; Lang, J.; Schuhle, U.; Solanki, S. K.; Wilhelm,
K.; Thompson, W. T.; Pike, C. D.; Ruedi, I.; Hollandt, J.; Huber,
M. C. E.
2002ISSIR...2..235P Altcode: 2002rcs..conf..235P; 2002ESASR...2..235P
Simultaneous observations of the same solar features with different
instruments provide a way to compare radiometric calibrations and
detect changes in responsivity with time of EUV instruments in space
within the combined uncertainties of the individual instruments. Here
we present the intercalibration of the SUMER (Solar Ultraviolet
Measurements of Emitted Radiation) instrument (detectors A and B) and
the two CDS (Coronal Diagnostic Spectrometer) instruments, the Normal
Incidence Spectrometer (NIS) and the Grazing Incidence Spectrometer
(GIS) on the Solar and Heliospheric Observatory (SOHO). This work
describes the results of the Joint Observing Programme Intercal 01
and presents quiet-Sun comparisons from March 1996 up to February
2001, which represents the complete set of all available Intercal
01 measurements. Recent calibration updates of both instruments are
employed, and the results indicate a very good correlation and agreement
of the measured radiances within the combined uncertainties.
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Title: Source Standards for the Radiometric Calibration of
Astronomical Instruments in the VUV Spectral Range Traceable to the
Primary Standard BESSY
Authors: Hollandt, J.; Kuhne, M.; Huber, M. C. E.; Wende, B.
2002ISSIR...2...51H Altcode: 2002rcs..conf...51H; 2002ESASR...2...51H
On the basis of a high-current hollow-cathode discharge we have
developed two transfer source standards suitable for the radiometric
calibration of vacuum-ultraviolet (VUV) telescopes. The source
standards are transportable and (in their current design) produce
collimated beams of 5 mm (grazing-incidence region) and 2.5 mm, 5 mm,
10 mm and 15 mm (normal-incidence region) diameter. By irradiating the
entrance aperture of the telescope with this beam, the overall spectral
response of the instrument can be determined and spectral-responsivity
variations over the entrance aperture can be directly evaluated. The
transfer standards described in this paper have been calibrated in the
radiometry laboratory of the Physikalisch-Technische Bundesanstalt
(PTB) by use of the calculable spectral photon flux of the Berlin
electron storage ring for synchrotron radiation BESSY I: a primary
radiometric VUV source standard. The output of the source standards
has been determined at 57 emission lines covering the wavelength range
15 nm to 150 nm. The photon flux in these emission lines ranges from
10 4 s-1 to 109 s-1 and the overall relative standard uncertainty of
the photon flux in any given line is found to be not more than 8 %.
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Title: The century of space science
Authors: Bleeker, J. A. M.; Geiss, J.; Huber, M. C. E.
2002css1.book....3B Altcode:
No abstract at ADS
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Title: Roger Bonnet, the scientist
Authors: Huber, Martin C. E.
2001ESASP.493...81H Altcode: 2001sefs.work...81H
Roger M. Bonnet, who has been Director of the Scienfific Programme
in the European Scace Agency for 18 years, is known to the younger
generation of solar physicists - those who will actually prepare and
operate the Solar Orbiter - in this role only. We appraise here Roger
Bonnet's research work, from his student time when he investigated the
ultraviolet solar spectrum by use of balloon and rocket instruments. We
then trace his research in solar physics as Principal Investigator on
the eighth Orbiting Solar Observatory (OSO-8) and, later, with the
Transition Region Camera (TRC). The results of these two projects,
respectively, ruled out significant wave heating of the corona
and provided the first high-resolution Lα images of the Sun. We
further review his contributions to cometary and stellar research,
and note his numerous contributions to science policy, i.e., his
role in inspiring and stimulating developments - be it by organising
influential conferences or by promoting his visions as member or
chairman of high-level committees - already before he became ESA's
Director of the Scientific Programme.
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Title: Comparison of quiet-Sun radiances measured by CDS and SUMER
on SOHO
Authors: Pauluhn, A.; Solanki, S. K.; Schühle, U.; Wilhelm, K.;
Lang, J.; Thompson, W. T.; Rüedi, I.; Hollandt, J.; Huber, M. C. E.
2001SSRv...97...63P Altcode:
Since the beginning of the SOHO (Solar and Heliospheric Observatory)
mission an intercalibration programme was carried out which included
simultaneous observations of the EUV instruments CDS (Coronal Diagnostic
Spectrometer) and SUMER (Solar Ultraviolet Measurements of Emitted
Radiation) of common targets on the quiet Sun. The observations in the
chromospheric line of He i (584 Å) and the two coronal lines of Mg x
(609 Å and 624 Å) thus cover the long period of 4 years and provide a
data set highly suitable not only for instrumental comparison but also
for studies of the quiet Sun's long term variability. Up to the SOHO
accident, both instruments show a very good temporal correlation and
stability. Even after the loss and recovery of the spacecraft, when
the instruments had been exposed to extreme temperature conditions,
the performance of the CDS and SUMER instruments is still good, as is
the temporal correlation. However, the ratio between the efficiencies
of the two instruments, which remained constant with time until the
SOHO accident seems to have changed afterwards. In the coronal lines
both instruments show an increase of average radiances towards the
solar maximum.
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Title: Gravitation II: The LISA Cornerstone
Authors: Huber, M. C. E.
2001ESASP.469...43H Altcode: 2001fpsr.conf...43H
No abstract at ADS
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Title: Radiance of Solar Spectral Lines observed with CDS and SUMER
on SOHO (CD-ROM Directory: contribs/pauluhn)
Authors: Pauluhn, A.; Schühle, U.; Solanki, S. K.; Rüedi, I.; Lang,
J.; Pike, C. D.; Thompson, W. T.; Huber, M. C. E.
2001ASPC..223..721P Altcode: 2001csss...11..721P
No abstract at ADS
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Title: Preface
Authors: Huber, M. C. E.; Jacob, M.
2001ESASP.469....1H Altcode: 2001fpsr.conf....1H
No abstract at ADS
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Title: Introduction
Authors: Huber, M. C. E.
2001ESASP.454...11H Altcode: 2001mrap.conf...11H
No abstract at ADS
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Title: Fundamental Physics in Space and Related Topics
Authors: Huber, M. C. E.; Jacob, M.; Battrick, B.
2001ESASP.469.....H Altcode: 2001fpsr.conf.....H
No abstract at ADS
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Title: Comparison of far-ultraviolet emission lines formed in coronal
holes and the quiet Sun
Authors: Stucki, K.; Solanki, S. K.; Schühle, U.; Rüedi, I.; Wilhelm,
K.; Stenflo, J. O.; Brković, A.; Huber, M. C. E.
2000A&A...363.1145S Altcode:
We present an analysis of 26 far-ultraviolet emission lines belonging
to 19 atoms and ions observed on both sides of the boundary of polar
coronal holes as well as other quiet Sun areas along the limb. The
observations were made with the SUMER instrument (Solar Ultraviolet
Measurements of Emitted Radiation) onboard the Solar and Heliospheric
Observatory (SOHO). We compare line intensities, shifts and widths
in coronal holes with the corresponding values obtained in the quiet
Sun. We find that with increasing formation temperature, spectral
lines show on average an increasingly stronger blueshift in coronal
holes relative to the quiet Sun at equal heliospheric angle, with the
coolest lines in our sample (formation temperature ~ 10<SUP>4</SUP>
K) indicating a small relative redshift. With respect to the rest
wavelength, however, only lines formed above 5 * 10<SUP>5</SUP> K
show blueshifts in coronal holes, which is not very different from
the quiet Sun. The width of the lines is generally larger (by a few
kilometers per second) inside the coronal hole. Intensity measurements
clearly show the presence of the coronal hole in Ne VIII lines as well
as in Fe XII, and provide evidence for a slightly enhanced emission
in polar coronal holes for lines formed below 10<SUP>5</SUP> K. This
last result is, however, less certain than the rest due to relatively
poor statistics. Intensity histograms also exhibit distinct differences
between coronal hole and quiet-Sun data. For cooler chromospheric lines,
such as Ni II, the coronal holes display a greater spread in intensities
than the quiet Sun. Transition-region lines, e.g. O IV, do not reveal
such differences, while Ne VIII shows characteristics of a coronal line
with lower average intensity and lower intensity spread inside holes.
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Title: Welcome Address
Authors: Huber, M. C. E.
2000ESASP.445....3H Altcode: 2000sfsl.conf....3H
No abstract at ADS
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Title: Commission 49: Interplanetary Plasma and Heliosphere:
(Plasma Interplanetaire et Heliosphere)
Authors: Verheest, F.; Vandas, M.; Buti, B.; Cramer, N. F.; Dryer, M.;
Habbal, S. R.; Hollweg, J. V.; Huber, M. C. E.; Kojima, M.; Ripken, H.
2000IAUTA..24...77V Altcode:
No abstract at ADS
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Title: Solar spectroradiometry with the telescope and spectrograph
SUMER on the Solar and Heliospheric Observatory SOHO
Authors: Wilhelm, K.; Schühle, U.; Curdt, W.; Dammasch, I. E.;
Hollandt, J.; Lemaire, P.; Huber, M. C. E.
2000Metro..37..393W Altcode:
No abstract at ADS
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Title: EUV brightness variations in the quiet Sun
Authors: Brković, A.; Rüedi, I.; Solanki, S. K.; Fludra, A.;
Harrison, R. A.; Huber, M. C. E.; Stenflo, J. O.; Stucki, K.
2000A&A...353.1083B Altcode:
The Coronal Diagnostic Spectrometer (CDS) onboard the SOHO satellite has
been used to obtain movies of quiet Sun regions at disc centre. These
movies were used to study brightness variations of solar features at
three different temperatures sampled simultaneously in the chromospheric
He I 584.3 Ä (2 * 10<SUP>4</SUP> K), the transition region O V 629.7
Ä (2.5 * 10<SUP>5</SUP> K) and coronal Mg IX 368.1 Ä (10<SUP>6</SUP>
K) lines. In all parts of the quiet Sun, from darkest intranetwork to
brightest network, we find significant variability in the He I and O
V line, while the variability in the Mg IX line is more marginal. The
relative variability, defined by rms of intensity normalised to the
local intensity, is independent of brightness and strongest in the
transition region line. Thus the relative variability is the same
in the network and the intranetwork. More than half of the points
on the solar surface show a relative variability, determined over a
period of 4 hours, greater than 15.5% for the O V line, but only 5%
of the points exhibit a variability above 25%. Most of the variability
appears to take place on time-scales between 5 and 80 minutes for the
He I and O V lines. Clear signs of “high variability” events are
found. For these events the variability as a function of time seen
in the different lines shows a good correlation. The correlation is
higher for more variable events. These events coincide with the (time
averaged) brightest points on the solar surface, i.e. they occur in
the network. The spatial positions of the most variable points are
identical in all the lines.
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Title: Alan Gabriel-A Career between Spectroscopy and the Sun
Authors: Huber, M. C. E.
1999ESASP.446....9H Altcode: 1999soho....8....9H
No abstract at ADS
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Title: Report on the activities of Space Science Department 1997
- 1998.
Authors: Huber, M. C. E.; Taylor, B. G.; Wenzel, K. -P.; Readings,
C. J.
1999roas.book.....H Altcode:
Contents: 1. Introduction. 2. Organisation and programme
overview. 3. Functional tasks (space science projects: XMM, Cluster-II,
INTEGRAL, Rosetta, FIRST, Planck, Mars Express; scientific aspects
of applications projects; space science operations: IUE, Hipparcos,
HST, Ulysses, ISO, SOHO, Cassini/Huygens; studies; general scientific
support). 4. Research. 5. Symposia and workshops.
---------------------------------------------------------
Title: An Empirical Model of a Polar Coronal Hole at Solar Minimum
Authors: Cranmer, S. R.; Kohl, J. L.; Noci, G.; Antonucci, E.;
Tondello, G.; Huber, M. C. E.; Strachan, L.; Panasyuk, A. V.;
Gardner, L. D.; Romoli, M.; Fineschi, S.; Dobrzycka, D.; Raymond,
J. C.; Nicolosi, P.; Siegmund, O. H. W.; Spadaro, D.; Benna, C.;
Ciaravella, A.; Giordano, S.; Habbal, S. R.; Karovska, M.; Li, X.;
Martin, R.; Michels, J. G.; Modigliani, A.; Naletto, G.; O'Neal,
R. H.; Pernechele, C.; Poletto, G.; Smith, P. L.; Suleiman, R. M.
1999ApJ...511..481C Altcode:
We present a comprehensive and self-consistent empirical model
for several plasma parameters in the extended solar corona above
a polar coronal hole. The model is derived from observations
with the SOHO Ultraviolet Coronagraph Spectrometer (UVCS/SOHO)
during the period between 1996 November and 1997 April. We compare
observations of H I Lyα and O VI λλ1032, 1037 emission lines
with detailed three-dimensional models of the plasma parameters and
iterate for optimal consistency between measured and synthesized
observable quantities. Empirical constraints are obtained for
the radial and latitudinal distribution of density for electrons,
H<SUP>0</SUP>, and O<SUP>5+</SUP>, as well as the outflow velocity
and unresolved anisotropic most probable speeds for H<SUP>0</SUP> and
O<SUP>5+</SUP>. The electron density measured by UVCS/SOHO is consistent
with previous solar minimum determinations of the white-light coronal
structure; we also perform a statistical analysis of the distribution
of polar plumes using a long time series. From the emission lines we
find that the unexpectedly large line widths of H<SUP>0</SUP> atoms
and O<SUP>5+</SUP> ions at most heights are the result of anisotropic
velocity distributions. These distributions are not consistent with
purely thermal motions or the expected motions from a combination of
thermal and transverse wave velocities. Above 2 R<SUB>solar</SUB>,
the observed transverse most probable speeds for O<SUP>5+</SUP> are
significantly larger than the corresponding motions for H<SUP>0</SUP>,
and the outflow velocities of O<SUP>5+</SUP> are also significantly
larger than the corresponding velocities of H<SUP>0</SUP>. Also, the
latitudinal dependence of intensity constrains the geometry of the
wind velocity vectors, and superradial expansion is more consistent
with observations than radial flow. We discuss the constraints and
implications on various theoretical models of coronal heating and
acceleration.
---------------------------------------------------------
Title: Space Research at the Threshold of the 21st Century - Aims
and Technologies
Authors: Huber, Martin C. E.
1999RvMA...12...47H Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Coronal Hole Properties Observed with SUMER
Authors: Stucki, K.; Solanki, S. K.; Rüedi, I.; Stenflo, J. O.;
Brković , A.; Schühle, U.; Wilhelm, K.; Huber, M. C. E.
1999SSRv...87..315S Altcode:
We analyze SUMER spectra of 14 lines belonging to 12 ions, obtained
on both sides of the boundary of polar coronal holes as well as at
other locations along the limb. We compare line intensities, shifts
and widths in coronal holes with values obtained in the quiet Sun. We
find that with increasing formation temperature, spectral lines show
an increasingly stronger blueshift in coronal holes relative to the
quiet Sun at an equal heliospheric angle. The width of the lines is
generally larger (by a few km/s) inside the coronal hole. Intensity
measurements show the presence of the coronal hole in Ne VIII lines
as well as in Fe XII, with evidence for a slightly enhanced emission
in polar coronal holes for lines formed below 10<SUP>5</SUP> K.
---------------------------------------------------------
Title: Coronal Holes Versus Normal Quiet Sun Observed with SUMER
Authors: Stucki, K.; Solanki, S. K.; Rüedi, I.; Stenflo, J. O.;
Brković, A.; Schühle, U.; Wilhelm, K.; Huber, M. C. E.
1999Ap&SS.264...53S Altcode: 1998Ap&SS.264...53S
We present a preliminary analysis of spectral lines obtained with the
SUMER instrument (Solar Ultraviolet Measurements of Emitted Radiation)
onboard the Solar and Heliospheric Observatory (SOHO), as observed
during three observing campaigns. From the 70 observed spectral lines,
we selected 12, representing 9 ions or atoms, in order to analyse line
intensities, shifts and widths in polar coronal holes as well as in the
normal quiet Sun. We find that coronal lines show a distinct blueshift
in coronal holes relative to the quiet Sun at equal heliospheric
angle, while there is no evidence for such a shift for lines formed at
temperatures below 10^5 K. The widths of lines formed at temperatures
above 3 - 10^4 K are slightly increased inside the coronal hole,
but unaffected for lower temperatures. Intensity measurements clearly
show the center-to-limb variation, as well as an intensity diminution
inside the coronal hole for lines formed above approximately 10^5 K.
---------------------------------------------------------
Title: COBRAS/SAMBA, Intermarsnet, MORO, STARS and STEP : the missions
studied for the M3 opportunity of Horizon 2000
Authors: Huber, M. C. E.; Harris, Robert A.
1999ESASP1216.....H Altcode: 1999csim.rept.....H
No abstract at ADS
---------------------------------------------------------
Title: Brightness Variations in the Solar Atmosphere as Seen by SOHO
Authors: Brkovic, A.; Rüedi, I.; Solanki, S. K.; Huber, M. C. E.;
Stenflo, J. O.; Stucki, K.; Harrison, R.; Fludra, A.
1999ASSL..239..231B Altcode: 1999msa..proc..231B
We present preliminary results of a statistical analysis of the
brightness variations of solar features at different levels in
the solar atmosphere. We observed quiet Sun regions at disc centre
using the Coronal Diagnostic Spectrometer (CDS) onboard the Solar and
Heliospheric Observatory (SOHO). We find significant variability at all
time scales in all parts of the quiet Sun, from darkest intranetwork
to brightest network. Such variations are observed simultaneously in
the chromospheric He I 584.33 Angstroms (2 \cdot 10^4 K) line, the
transition region O V 629.74 Angstroms (2.5 \cdot 10^5 K) and coronal
Mg IX 368.06 Angstroms (10^6 K) line. The relative variability is
independent of brightness and most of the variability appears to take
place on time scales longer than 5 minutes for all 3 spectral lines. No
significant differences are observed between the different data sets.
---------------------------------------------------------
Title: Solar irradiances of UV and EUV lines during the minimum of
the sunspot activity in 1996
Authors: Wilhelm, K.; Lemaire, P.; Dammasch, I. E.; Hollandt, J.;
Schühle, U.; Curdt, W.; Kucera, T.; Hassler, D. M.; Huber, M. C. E.
1999AdSpR..24..229W Altcode:
Full Sun observations in UV and EUV emission lines were performed
by SUMER (Solar Ultraviolet Measurements of Emitted Radiation) on
SOHO (Solar and Heliospheric Observatory) in 1996. The radiometric
preflight calibration of SUMER is traceable to a primary radiometric
source standard - the electron storage ring BESSY. Based on this
calibration and on its inflight refinements, the irradiance values at
SOHO have been obtained for the lines He i (λ584.33), O v (λ629.74),
Ne viii (λ770.41), S v (λ786.47), O iv (λ787.72), S vi (λλ933.39,
944.52), H i Ly ɛ (λ937.80), C iii (λ977.04), N v (λ1238.81),
Si i (λ1256.52), and C iv (λ1548.20), and the continuum near 1549
Å. In this contribution, we compare our measurements with other recent
irradiance determinations and discuss, in particular, the observations
in the C iv line.
---------------------------------------------------------
Title: COBRAS/SAMBA, Intermarsnet, MORO, STARS and STEP : the missions
studied for the M3 opportunity of Horizon 2000
Authors: Huber, M. C. E.; Harris, Bob
1999csim.book.....H Altcode:
No abstract at ADS
---------------------------------------------------------
Title: UVCS/SOHO Empirical Determinations of Anisotropic Velocity
Distributions in the Solar Corona
Authors: Kohl, J. L.; Noci, G.; Antonucci, E.; Tondello, G.; Huber,
M. C. E.; Cranmer, S. R.; Strachan, L.; Panasyuk, A. V.; Gardner,
L. D.; Romoli, M.; Fineschi, S.; Dobrzycka, D.; Raymond, J. C.;
Nicolosi, P.; Siegmund, O. H. W.; Spadaro, D.; Benna, C.; Ciaravella,
A.; Giordano, S.; Habbal, S. R.; Karovska, M.; Li, X.; Martin, R.;
Michels, J. G.; Modigliani, A.; Naletto, G.; O'Neal, R. H.; Pernechele,
C.; Poletto, G.; Smith, P. L.; Suleiman, R. M.
1998ApJ...501L.127K Altcode:
We present a self-consistent empirical model for several plasma
parameters of a polar coronal hole near solar minimum, derived from
observations with the Solar and Heliospheric Observatory Ultraviolet
Coronagraph Spectrometer. The model describes the radial distribution of
density for electrons, H<SUP>0</SUP>, and O<SUP>5+</SUP> and the outflow
velocity and unresolved most probable velocities for H<SUP>0</SUP>
and O<SUP>5+</SUP> during the period between 1996 November and 1997
April. In this Letter, we compare observations of H I Lyα and O
VI λλ1032, 1037 emission lines with spatial models of the plasma
parameters, and we iterate for optimal consistency between measured and
synthesized observable quantities. The unexpectedly large line widths
of H<SUP>0</SUP> atoms and O<SUP>5+</SUP> ions at most radii are the
result of anisotropic velocity distributions, which are not consistent
with purely thermal motions or the expected motions from a combination
of thermal and transverse wave velocities. Above 2 R<SUB>solar</SUB>,
the observed transverse, most probable speeds for O<SUP>5+</SUP> are
significantly larger than the corresponding motions for H<SUP>0</SUP>,
and the outflow velocities of O<SUP>5+</SUP> are also significantly
larger than the corresponding velocities of H<SUP>0</SUP>. We discuss
the constraints and implications on various theoretical models of
coronal heating and acceleration.
---------------------------------------------------------
Title: Introduction
Authors: Huber, M. C. E.
1998ESASP.431....3H Altcode: 1998sslt.conf....3H
No abstract at ADS
---------------------------------------------------------
Title: Space science and the long-term future of space in Europe
Authors: Huber, M. C. E.; Battrick, B.; Guyenne, T. D.
1998ESASP.431.....H Altcode: 1998sslt.conf.....H
No abstract at ADS
---------------------------------------------------------
Title: Solar irradiances and radiances of UV and EUV lines during
the minimum of sunspot activity in 1996
Authors: Wilhelm, K.; Lemaire, P.; Dammasch, I. E.; Hollandt, J.;
Schuehle, U.; Curdt, W.; Kucera, T.; Hassler, D. M.; Huber, M. C. E.
1998A&A...334..685W Altcode:
Full Sun observations in UV and EUV emission lines were performed
by SUMER (Solar Ultraviolet Measurements of Emitted Radiation) on
SOHO (Solar and Heliospheric Observatory) in 1996. The radiometric
pre-flight calibration of SUMER is traceable to a primary radiometric
source standard - the electron storage ring BESSY. Based on this
calibration, the irradiance values at SOHO and at 1 AU have been
obtained for the lines He i (lambda 584.33 { Angstroms}), O v (lambda
629.74 { Angstroms}), Ne viii (lambda 770.41 { Angstroms}), S v (lambda
786.47 { Angstroms}), O iv (lambda 787.72 { Angstroms}), S vi (lambda
lambda 933.39, 944.52 { Angstroms}), H i Ly epsilon (lambda 937.80 {
Angstroms}), C iii (lambda 977.04 { Angstroms}), N v (lambda 1238.81
{ Angstroms}), Si i (lambda 1256.52 { Angstroms}), and C iv (lambda
1548.20 { Angstroms}). The spatially resolved measurements allowed
good estimates to be made of the active region contributions to the
irradiance of the quiet Sun. The centre-to-limb radiance variations of
these lines have also been obtained from these measurements. For quiet
solar conditions, a radiance spectrum was determined for wavelengths
from 800 { Angstroms} to 1500 { Angstroms} near the centre of the
solar disk.
---------------------------------------------------------
Title: The Solar Corona Above Polar Coronal Holes as Seen by SUMER
on SOHO
Authors: Wilhelm, Klaus; Marsch, Eckart; Dwivedi, Bhola N.; Hassler,
Donald M.; Lemaire, Philippe; Gabriel, Alan H.; Huber, Martin C. E.
1998ApJ...500.1023W Altcode:
In order to address two of the principal scientific objectives of the
Solar and Heliospheric Observatory (SOHO), studies of the heating
mechanisms of the solar corona and the acceleration processes of
the solar wind, we deduce electron temperatures, densities, and
ion velocities in plumes and interplume regions of polar coronal
holes using ultraviolet observations from SUMER (Solar Ultraviolet
Measurements of Emitted Radiation) on SOHO. SUMER allows us to study
the inner corona up to a distance of about 430,000 km above the
limb, or r = 1.6 R<SUB>⊙</SUB> (solar radius) from the center
of the disk. We find the electron temperatures, T<SUB>e</SUB>,
to be less than 800,000 K in a plume in the range from r = 1.03 to
1.60 R<SUB>⊙</SUB>, decreasing with height to ~330,000 K. Near
an interplume lane, the electron temperature is also low, but stays
between 750,000 and 880,000 K in the same height interval. Doppler
widths of O VI lines in plumes are narrower (Δλ<SUB>D</SUB> ~
150 mÅ, v<SUB>1/E</SUB> ~ 43 km s<SUP>-1</SUP>) than in interplume
lanes (~190 mÅ, ~55 km s<SUP>-1</SUP>). The thermal and turbulent
ion speeds, v<SUB>1/E</SUB>, of Si<SUP>7+</SUP> reach values up to
~80 km s<SUP>-1</SUP> in the darkest regions outside plumes above the
coronal hole. This corresponds to a kinetic ion temperature of 1 ×
10<SUP>7</SUP> K. A limit of ~18 km s<SUP>-1</SUP> for the bulk speed
in plumes below r = 1.2 R<SUB>⊙</SUB> is deduced from O VI line shift
measurements and consideration of the three-dimensional plume geometry
(differential line-of-sight velocities <=3 km s<SUP>-1</SUP>),
whereas differential line-of-sight velocities of Mg<SUP>8+</SUP>
ions up to 34 km s<SUP>-1</SUP> can be seen in dark regions.
---------------------------------------------------------
Title: Foreword
Authors: Fröhlich, C.; Huber, M. C. E.; Solanki, S. K.; von Steiger,
R.
1998SSRv...85...11F Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Solar Composition and Its Evolution -- From Core to Corona
Authors: Fröhlich, C.; Huber, M. C. E.; Solanki, S. K.; von Steiger,
R.
1998sce..conf.....F Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Future Mission Possibilities Within ESA
Authors: Huber, M. C. E.; Coradini, M.
1998ESASP.417...67H Altcode: 1998cesh.conf...67H
No abstract at ADS
---------------------------------------------------------
Title: Solar composition and its evolution - from core to
corona. Proceedings. ISSI (International Space Science Institute)
Workshop, Bern (Switzerland), 26 - 30 Jan 1998.
Authors: Fröhlich, C.; Huber, M. C. E.; Solanki, S. K.; von Steiger,
R.
1998SSRv...85.....F Altcode:
The following topics were dealt with: solar composition, solar
evolution, the solar interior, helioseismology, photosphere,
chromosphere, solar corona, solar wind, the Sun as a Sun-like star.
---------------------------------------------------------
Title: Introduction
Authors: Huber, M. C. E.
1998suco.conf....3H Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Velocity Fields in the Solar Corona during Mass Ejections as
Observed with UVCS-SOHO
Authors: Antonucci, E.; Kohl, J. L.; Noci, G.; Tondello, G.; Huber,
M. C. E.; Gardner, L. D.; Nicolosi, P.; Giordano, S.; Spadaro, D.;
Ciaravella, A.; Raymond, C. J.; Naletto, G.; Fineschi, S.; Romoli, M.;
Siegmund, O. H. W.; Benna, C.; Michels, J.; Modigliani, A.; Panasyuk,
A.; Pernechele, C.; Smith, P. L.; Strachan, L.; Ventura, R.
1997ApJ...490L.183A Altcode:
This Letter presents the observations of the first two coronal mass
ejections (CMEs) obtained with the Ultraviolet Coronagraph Spectrometer
of SOHO. Both CMEs were observed at high spectral resolution in the
ultraviolet domain. The first event on 1996 June 6-7 was observed in H I
Lyα λ1216 and Lyβ λ1026, O VI λλ1032 and 1037, Si XII λλ499 and
521 and imaged within 1.5 and 5 R<SUB>solar</SUB>. The second event on
1996 December 23 was observed in several H I lines and cool lines such
as C III λ977, N III λλ990-992, and O V λ630. The analysis of line
profiles has allowed us to determine the line-of-sight velocities of the
extended corona during a mass ejection. In particular there is evidence
for mass motions consistent with untwisting magnetic fields around an
erupted flux tube in one of the events and line of sight velocities of
200 km s<SUP>-1</SUP> in the early phase of the second event presumably
related to the expansion of the leading arch of the transient.
---------------------------------------------------------
Title: Welcome/Introduction
Authors: Huber, M. C. E.
1997ESASP.415....3H Altcode: 1997cpsh.conf....3H
No abstract at ADS
---------------------------------------------------------
Title: Composition of Coronal Streamers from the SOHO Ultraviolet
Coronagraph Spectrometer
Authors: Raymond, J. C.; Kohl, J. L.; Noci, G.; Antonucci, E.;
Tondello, G.; Huber, M. C. E.; Gardner, L. D.; Nicolosi, P.; Fineschi,
S.; Romoli, M.; Spadaro, D.; Siegmund, O. H. W.; Benna, C.; Ciaravella,
A.; Cranmer, S.; Giordano, S.; Karovska, M.; Martin, R.; Michels, J.;
Modigliani, A.; Naletto, G.; Panasyuk, A.; Pernechele, C.; Poletto,
G.; Smith, Peter L.; Suleiman, R. M.; Strachan, L.
1997SoPh..175..645R Altcode:
The Ultraviolet Coronagraph Spectrometer on the SOHO satellite covers
the 940-1350 Å range as well as the 470-630 Å range in second
order. It has detected coronal emission lines of H, N, O, Mg, Al, Si,
S, Ar, Ca, Fe, and Ni, particularly in coronal streamers. Resonance
scattering of emission lines from the solar disk dominates the
intensities of a few lines, but electron collisional excitation produces
most of the lines observed. Resonance, intercombination and forbidden
lines are seen, and their relative line intensities are diagnostics
for the ionization state and elemental abundances of the coronal gas.
---------------------------------------------------------
Title: First Results from the SOHO Ultraviolet Coronagraph
Spectrometer
Authors: Kohl, J. L.; Noci, G.; Antonucci, E.; Tondello, G.; Huber,
M. C. E.; Gardner, L. D.; Nicolosi, P.; Strachan, L.; Fineschi, S.;
Raymond, J. C.; Romoli, M.; Spadaro, D.; Panasyuk, A.; Siegmund,
O. H. W.; Benna, C.; Ciaravella, A.; Cranmer, S. R.; Giordano, S.;
Karovska, M.; Martin, R.; Michels, J.; Modigliani, A.; Naletto, G.;
Pernechele, C.; Poletto, G.; Smith, P. L.
1997SoPh..175..613K Altcode:
The SOHO Ultraviolet Coronagraph Spectrometer (UVCS/SOHO) is being
used to observe the extended solar corona from 1.25 to 10 R⊙ from
Sun center. Initial observations of polar coronal holes and equatorial
streamers are described. The observations include measurements of
spectral line profiles for HI Lα and Lβ, Ovi 1032 Å and 1037 Å,
Mgx 625 Å, Fexii 1242 Å and several others. Intensities for Mgx
610 Å, Sixii 499 Å, and 520 Å, Sx 1196 Å, and 22 others have been
observed. Preliminary results for derived H<SUP>0</SUP>, O<SUP>5+</SUP>,
Mg<SUB>9+</SUB>, and Fe<SUP>11+</SUP> velocity distributions and initial
indications of outflow velocities for O<SUP>5+</SUP> are described. In
streamers, the H<SUP>0</SUP> velocity distribution along the line of
sight (specified by the value at e<SUP>-1</SUP>, along the line of
sight) decreases from a maximum value of about 180 km s<SUP>-1</SUP>
at 2 R⊙ to about 140 km s<SUP>-1</SUP> at 8 R⊙. The value for
O<SUP>5+</SUP> increases with height reaching a value of 150 km
s<SUP>-1</SUP> at 4.7 R⊙. In polar coronal holes, the O<SUP>5+</SUP>
velocity at e<SUP>-1</SUP> is about equal to that of H<SUP>0</SUP>
at 1.7 R⊙ and significantly larger at 2.1 R⊙. The O<SUP>5+</SUP>
in both streamers and coronal holes were found to have anisotropic
velocity distributions with the smaller values in the radial direction.
---------------------------------------------------------
Title: Report on the activities of Space Science Department. 1995
- 1996.
Authors: Huber, M. C. E.; Taylor, B. G.; Wenzel, K. -P.
1997roas.book.....H Altcode:
Contents: 1. Introduction. 2. Organisation and programme
overview. 3. Functional tasks (Projects: Cluster, Cassini/Huygens,
XMM, INTEGRAL, Rosetta, FIRST, Planck. Science operations: IUE,
Hipparcos, HST, Ulysses, ISO, SOHO. Studies. General scientific
support). 4. Research. 5. Symposia and workshops.
---------------------------------------------------------
Title: Empirical Models of the Extended Solar Corona
Authors: Kohl, J. L.; Noci, G.; Antonucci, E.; Ciaravella, A.;
Cranmer, S.; Dobrzycka, D.; Fineschi, S.; Gardner, L. D.; Huber,
M. C. E.; Panasyuk, A.; Raymond, J. C.; Strachan, L.
1997SPD....28.0303K Altcode: 1997BAAS...29..907K
Ultraviolet spectroscopy is being used to produce self consistent
empirical models of polar coronal holes and equatorial streamers in the
extended solar corona. The models are intended to provide experimental
values for many of the primary plasma parameters of the extended corona,
which can then be used to constrain theoretical coronal and solar
wind models. The empirical models are based on synoptic observations
and other measurements of spectral line profiles and intensities of
H I Lyalpha , O VI 1032 Angstroms and 1037 Angstroms, Fe XII 1242
Angstroms, Mg X 625 Angstroms and several others. Information about
velocity distributions, outflow velocities, densities and elemental
abundances as derived from the observations are specified in the
models. The models used to specify the empirically derived parameters
include a description of well established theoretical processes such
as those controlling ionization balance, collisional excitation,
and resonant scattering. They do not include any descriptions of
less well established processes such as heating functions, transverse
wave motions or direct momentum deposition by waves. The intent is to
provide, to the maximum extent possible, empirical descriptions that
can be used, together with theoretical models, to help identify the
dominant physical processes responsible for coronal heating, solar wind
acceleration and the chemical composition of the solar wind. This work
is supported by NASA Grant NAG5-3192 to the Smithsonian Astrophysical
Observatory, the Italian Space Agency and Swiss funding sources.
---------------------------------------------------------
Title: O^{5+} Acceleration by Turbulence in Polar Coronal Holes
Authors: Fletcher, L.; Huber, M. C. E.
1997ESASP.404..379F Altcode: 1997cswn.conf..379F
No abstract at ADS
---------------------------------------------------------
Title: Measurements of H I and O VI velocity distributions in the
extended solar corona with UVCS/SOHO and UVCS/Spartan 201
Authors: Kohl, J. H.; Noci, G.; Antonucci, E.; Tondello, G.; Huber,
M. C. E.; Gardner, L. D.; Nicolosi, P.; Fineschi, S.; Raymond, J. C.;
Romoli, M.; Spadaro, D.; Siegmund, O. H. W.; Benna, C.; Ciaravella,
A.; Cranmer, S. R.; Giordano, S.; Karovska, M.; Martin, R.; Michels,
J.; Modigliani, A.; Naletto, G.; Panasyuk, A.; Pernechele, C.; Poletto,
G.; Smith, P. L.; Strachan, L.
1997AdSpR..20....3K Altcode:
The Ultraviolet Coronagraph Spectrometer on the Solar and Heliospheric
Observatory, UVCS/SOHO, and the Ultraviolet Coronal Spectrometer on
the Spartan 201 satellite, UVCS/Spartan, have been used to measure
H I 1215.67 A˚ line profiles in polar coronal holes of the Sun at
projected heliocentric heights between 1.5 and 3.0 R_solar. UVCS/SOHO
also measured line profiles for H I 1025.72 A˚, O VI 1032/1037 A˚,
and Mg X 625 A˚. The reported UVCS/SOHO observations were made between
5 April and 21 June 1996 and the UVCS/Spartan observations were made
between 11 and 12 April 1993. Both sets of measurements indicate that a
significant fraction of the protons along the line of sight in coronal
holes have velocities larger than those for a Maxwellian velocity
distribution at the expected electron temperature. Most probable
speeds for O^5+ velocity distributions along the lines of sight are
smaller than those of H^0 at 1.5 R_solar, are comparable at about 1.7
R_solar and become significantly larger than the H^0 velocities above
2 R_solar. There is a tendency for the O^5+ line of sight velocity
distribution in concentrations of polar plumes to be more narrow than
those in regions away from such concentrations. UVCS/SOHO has identified
31 spectral lines in the extended solar corona.
---------------------------------------------------------
Title: First Results of the SUMER Telescope and Spectrometer on SOHO -
I. Spectra and Spectroradiometry
Authors: Wilhelm, K.; Lemaire, P.; Curdt, W.; Schühle, U.; Marsch, E.;
Poland, A. I.; Jordan, S. D.; Thomas, R. J.; Hassler, D. M.; Huber,
M. C. E.; Vial, J. -C.; Kühne, M.; Siegmund, O. H. W.; Gabriel, A.;
Timothy, J. G.; Grewing, M.; Feldman, U.; Hollandt, J.; Brekke, P.
1997SoPh..170...75W Altcode:
SUMER - the Solar Ultraviolet Measurements of the Emitted Radiation
instrument on the Solar and Heliospheric Observatory (SOHO) - observed
its first light on January 24, 1996, and subsequently obtained a
detailed spectrum with detector B in the wavelength range from 660
to 1490 Å (in first order) inside and above the limb in the north
polar coronal hole. Using detector A of the instrument, this range
was later extended to 1610 Å. The second-order spectra of detectors
A and B cover 330 to 805 Å and are superimposed on the first-order
spectra. Many more features and areas of the Sun and their spectra
have been observed since, including coronal holes, polar plumes and
active regions. The atoms and ions emitting this radiation exist at
temperatures below 2 × 10<SUP>6</SUP> K and are thus ideally suited
to investigate the solar transition region where the temperature
increases from chromospheric to coronal values. SUMER can also be
operated in a manner such that it makes images or spectroheliograms
of different sizes in selected spectral lines. A detailed line profile
with spectral resolution elements between 22 and 45 mÅ is produced for
each line at each spatial location along the slit. From the line width,
intensity and wavelength position we are able to deduce temperature,
density, and velocity of the emitting atoms and ions for each emission
line and spatial element in the spectroheliogram. Because of the high
spectral resolution and low noise of SUMER, we have been able to detect
faint lines not previously observed and, in addition, to determine
their spectral profiles. SUMER has already recorded over 2000 extreme
ultraviolet emission lines and many identifications have been made on
the disk and in the corona.
---------------------------------------------------------
Title: First Results from UVCS: Dynamics of the Extended Corona
Authors: Antonucci, E.; Noci, G.; Kohl, J. L.; Tondello, G.; Huber,
M. C. E.; Giordano, S.; Benna, C.; Ciaravella, A.; Fineschi, S.;
Gardner, L. D.; Martin, R.; Michels, J.; Naletto, G.; Nicolosi, P.;
Panasyuk, A.; Raymond, C. J.; Romoli, M.; Spadaro, D.; Strachan, L.;
van Ballegooijen, A.
1997ASPC..118..273A Altcode: 1997fasp.conf..273A
The Ultraviolet Coronagraph Spectrometer (UVCS) started to observe
the Sun at the end of January 1996. Here we present a selection of
results obtained with the UVCS in the first months of operation. UV
spectral line profiles in coronal holes, and in general in regions
with open magnetic field lines, are much broader than in closed
field line regions; that is, line-of-sight velocities are much
larger in open field lines . Polar plumes have narrower profiles
than interplume regions. The O VI ratio diagnostics indicates that in
polar coronal holes the outflow velocity is progressively increasing
with heliodistance and exceeds 100 km/sec near 2--2.5 solar radii. A
coronal mass ejection observation has revealed line--of--sight plasma
motions of 100 km/sec and a complex dynamics.
---------------------------------------------------------
Title: Properties of Brightenings Seen in CDS Movies
Authors: Rüedi, I.; Brkovic, A.; Solanki, S. K.; Harrison, R.;
Fludra, A.; Huber, M. C. E.; Stenflo, J. O.; Stucki, K.
1997ESASP.404..641R Altcode: 1997cswn.conf..641R
No abstract at ADS
---------------------------------------------------------
Title: First results from UVCS/SOHO
Authors: Noci, G.; Kohl, J. L.; Antonucci, E.; Tondello, G.; Huber,
M. C. E.; Fineschi, S.; Gardner, L. D.; Naletto, G.; Nicolosi, P.;
Raymond, J. C.; Romoli, M.; Spadaro, D.; Siegmund, O. H. W.; Benna, C.;
Ciaravella, A.; Giordano, S.; Michels, J.; Modigliani, A.; Panasyuk,
A.; Pernechele, C.; Poletto, G.; Smith, P. L.; Strachan, L.
1997AdSpR..20.2219N Altcode:
We present here the first results obtained by the Ultraviolet
Coronagraph Spectrometer (UVCS) operating on board the SOHO
satellite. The UVCS started to observe the extended corona at the end
of January 1996; it routinely obtains coronal spectra in the 1145 A˚ -
1287 A˚, 984 A˚ - 1080 A˚ ranges, and intensity data in the visible
continuum. Through the composition of slit images it also produces
monocromatic images of the extended corona. The performance of the
instrument is excellent and the data obtained up to now are of great
interest. We briefly describe preliminary results concerning polar
coronal holes, streamers and a coronal mass ejection, in particular: the
very large r.m.s. velocities of ions in polar holes (hundreds km/sec
for OVI and MgX); the puzzling difference between the HI Ly-alpha
image and that in the OVI resonance doublet, for most streamers; the
different signatures of the core and external layers of the streamers
in the width of the ion lines and in the OVI doublet ratio, indicating
larger line-of-sight (l.o.s.) and outflow velocities in the latter.
---------------------------------------------------------
Title: First Results of the SUMER Telescope and Spectrometer on SOHO -
II. Imagery and Data Management
Authors: Lemaire, P.; Wilhelm, K.; Curdt, W.; SchÜle, U.; Marsch,
E.; Poland, A. I.; Jordan, S. D.; Thomas, R. J.; Hassler, D. M.; Vial,
J. C.; KÜhne, M.; Huber, M. C. E.; Siegmund, O. H. W.; Gabriel, A.;
Timothy, J. G.; Grewing, M.
1997SoPh..170..105L Altcode:
SUMER - Solar Ultraviolet Measurements of Emitted Radiation - is not
only an extreme ultraviolet (EUV) spectrometer capable of obtaining
detailed spectra in the range from 500 to 1610 Å, but, using the
telescope mechanisms, it also provides monochromatic images over
the full solar disk and beyond, into the corona, with high spatial
resolution. We report on some aspects of the observation programmes
that have already led us to a new view of many aspects of the Sun,
including quiet Sun, chromospheric and transition region network,
coronal hole, polar plume, prominence and active region studies. After
an introduction, where we compare the SUMER imaging capabilities to
previous experiments in our wavelength range, we describe the results
of tests performed in order to characterize and optimize the telescope
under operational conditions. We find the spatial resolution to be
1.2 arc sec across the slit and 2 arc sec (2 detector pixels) along
the slit. Resolution and sensitivity are adequate to provide details
on the structure, physical properties, and evolution of several solar
features which we then present. Finally some information is given on
the data availability and the data management system.
---------------------------------------------------------
Title: High-Resolution Observations of the Extreme Ultraviolet Sun
Authors: Harrison, R. A.; Fludra, A.; Pike, C. D.; Payne, J.;
Thompson, W. T.; Poland, A. I.; Breeveld, E. R.; Breeveld, A. A.;
Culhane, J. L.; Kjeldseth-Moe, O.; Huber, M. C. E.; Aschenbach, B.
1997SoPh..170..123H Altcode:
This paper presents first results of the Coronal Diagnostic Spectrometer
(CDS) recently launched aboard the Solar and Heliospheric Observatory
(SOHO). CDS is a twin spectrometer, operating in the extreme ultraviolet
range 151-785 Å. Thus, it can detect emission lines from trace
elements in the corona and transition region which will be used to
provide diagnostic information on the solar atmosphere. In this paper,
we present early spectra and images, to illustrate the performance of
the instrument and to pave the way for future studies.
---------------------------------------------------------
Title: The quiescent corona and slow solar wind
Authors: Noci, G.; Kohl, J. L.; Antonucci, E.; Tondello, G.; Huber,
M. C. E.; Fineschi, S.; Gardner, L. D.; Korendyke, C. M.; Nicolosi,
P.; Romoli, M.; Spadaro, D.; Maccari, L.; Raymond, J. C.; Siegmund,
O. H. W.; Benna, C.; Ciaravella, A.; Giordano, S.; Michels, J.;
Modigliani, A.; Naletto, G.; Panasyuk, A.; Pernechele, C.; Poletto,
G.; Smith, P. L.; Strachan, L.
1997ESASP.404...75N Altcode: 1997cswn.conf...75N; 1997soho....5...75N
No abstract at ADS
---------------------------------------------------------
Title: SOHO - A Global View of Sun and Heliosphere
Authors: Huber, M. C. E.
1997ICRC....8...39H Altcode: 1997ICRC...25h..39H
No abstract at ADS
---------------------------------------------------------
Title: Extreme ultraviolet observations of the solar corona: first
results from the coronal diagnostic spectrometer on SOHO
Authors: Harrison, R. A.; Fludra, A.; Sawyer, E. C.; Culhane, J. L.;
Norman, K.; Poland, A. I.; Thompson, W. T.; Kjeldseth-Moe, O.;
Aschenbach, B.; Huber, M. C. E.; Gabriel, A. H.; Mason, H. E.
1997AdSpR..20.2239H Altcode:
We present first results from the Coronal Diagnostic Spectrometer (CDS)
aboard the ESA/NASA Solar and Heliospheric Observatory (SOHO). CDS is
a double spectrometer operating in the 151-785 A˚ range. This region
of the solar spectrum is rich in emission lines from trace elements
in the solar atmosphere, which can be used to derive diagnostic
information on coronal and transition region plasma. Early spectra are
presented and well identified lines are listed. In addition, examples
of images in selected wavelength ranges are shown, for a prominence,
a loop system and a bright point, demonstrating well the power of such
extreme ultraviolet observations.
---------------------------------------------------------
Title: Opening remarks
Authors: Huber, M. C. E.
1996ESASP.388D...9H Altcode: 1996sfis.confD...9H
No abstract at ADS
---------------------------------------------------------
Title: In-Flight Performance of the SOHO Ultraviolet Coronagraph
Spectrometer
Authors: Gardner, L. D.; Kohl, J. L.; Noci, G.; Antonucci, E.;
Tondello, G.; Huber, M. C. E.; Ciaravella, A.; Fineschi, S.; Giordano,
S.; Moran, T.; Naletto, G.; Nicolosi, P.; Romoli, M.; Strachan,
L.; Benna, C.; Pernechele, C.; Raymond, J. C.; Siegmund, O. H. W.;
Spadaro, D.; Smith, P. L.
1996AAS...188.3705G Altcode: 1996BAAS...28..878G
The in-flight performance of the SOHO Ultraviolet Coronagraph
Spectrometer (UVCS/SOHO) is consistent with the pre-launch
characterization and meets all planned observational
requirements. Measurements of the key UVCS/SOHO performance
characteristics have been performed. This paper describes the
measurement techniques and the results. In-flight values for the
spectral and spatial resolutions, wavelength scales, the flat
fields, the geometric distortions, radiometric calibrations,
and stray light levels for the two ultraviolet channels have been
determined. Comparisons will be made to pre-flight measurements at both
the component level and system level. This work is supported by NASA
under contract NAS5-31250 to the Smithsonian Astrophysical Observatory,
by the Italian Space Agency and by Switzerland.
---------------------------------------------------------
Title: The history of thge SOHO mission.
Authors: Huber, M. C. E.; Bonnet, R. M.; Dale, D. C.; Arduini, M.;
Fröhlich, C.; Domingo, V.; Whitcomb, G.
1996ESABu..86...25H Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Spectroscopic Diagnostic Techniques with the SOHO Ultraviolet
Coronagraph Spectrometer
Authors: Romoli, M.; Kohl, J. L.; Noci, G.; Antonucci, E.; Tondello,
G.; Huber, M. C. E.; Fineschi, S.; Karovska, M.; Moran, T.; Strachan,
L.; Ciaravella, A.; Benna, C.; Gardner, L. D.; Giordano, S.; Naletto,
G.; Nicolosi, P.; Raymond, J. C.; Siegmund, O. H. W.; Spadaro, D.;
Smith, P. L.
1996AAS...188.3703R Altcode: 1996BAAS...28R.877R
The SOHO Ultraviolet Coronagraph Spectrometer (UVCS/SOHO) uses
spectroscopic diagnostic techniques and polarimetry to determine
velocity distributions, temperatures, outflow velocities and densities
of protons, electrons, and several minor ions in the extended solar
corona. This paper describes the initial use of these techniques with
UVCS/SOHO. Velocity distributions are derived from the observed spectral
line profiles. In some cases, grating scans are used to improve the
spectral resolution. The Doppler dimming method is used to determine
radial outflow velocities and spectral line shifts are used for line of
sight velocity measurements. The electron densities are derived from
visible polarized radiance measurements. The status of attempts to
derive electron temperatures from observations of electron scattered
HI Lyman-alpha will be presented. This research is supported by NASA
Contract NAS5-31250 to the Smithsonian Astrophysical Observatory,
by the Italian Space Agency and by Switzerland.
---------------------------------------------------------
Title: Ultraviolet Imaging of the Extended Solar Corona with the
SOHO Ultraviolet Coronagraph Spectrometer
Authors: Noci, G.; Kohl, J. L.; Antonucci, E.; Tondello, G.; Huber,
M. C. E.; Strachan, L.; Giordano, S.; Panasyuk, A.; Benna, C.;
Ciaravella, A.; Fineschi, S.; Gardner, L. D.; Naletto, G.; Nicolosi,
P.; Raymond, J. C.; Romoli, M.; Siegmund, O. H. W.; Spadaro, D.;
Smith, P. L.
1996AAS...188.3701N Altcode: 1996BAAS...28..877N
Spectroscopic observations of the extended solar corona with the SOHO
Ultraviolet Coronagraph Spectrometer (UVCS/SOHO) can be used to produce
images of the extended solar corona in several ultraviolet spectral
lines. The images are produced by scanning coronal images across the
spectrometer entrance slits. The slits intercept a 40 arcminute slice of
the corona parallel to the limb tangent. Telescope mirror motions can
be used to scan from about 1.25 to 10 R_⊙. The instrument is rolled
about its Sun-center axis to obtain images of the full corona. The
spatial resolution depends on the selected slit width and the combined
resolution of the spectrometer and XDL detectors. It is limited by
diffraction for observations near the Sun where only a narrow strip of
the telescope mirror is unvignetted by the external occulter. Images
of equatorial streamers in HI Lyman-alpha and beta, and in O VI 103.2
nm will be presented. Ultraviolet images of polar plumes will also be
provided. In some cases, interpolation techniques are used to fill-in
gaps in the raster pattern. This research is supported by NASA Contract
NAS5-31250 to the Smithsonian Astrophysical Observatory, by the Italian
Space Agency and by Switzerland.
---------------------------------------------------------
Title: Coordinated SOHO Observations of Polar Plumes: Ultraviolet
Spectroscopy with UVCS
Authors: Fineschi, S.; Kohl, J. L.; Noci, G.; Antonucci, E.;
Tondello, G.; Huber, M. C. E.; Gardner, L. D.; Giordano, S.; Romoli,
M.; Benna, C.; Ciaravella, A.; Naletto, G.; Nicolosi, P.; Raymond,
J. C.; Siegmund, O. H. W.; Spadaro, D.; Smith, P. L.; Strachan, L.
1996AAS...188.3704F Altcode: 1996BAAS...28..877F
The SOHO Ultraviolet Coronagraph Spectrometer (UVCS/SOHO) observed polar
plumes at the south polar coronal hole on 7 March 1996. Observations
were made in H I Ly-alpha, Ly-beta and O VI 103.2 and 103.7
nm. Heliocentric heights from 1.5 to 3.2 R_⊙ were observed. In
addition, HI Ly-alpha observations with 60 sec time resolution were
obtained at a heliocentric height of 1.6 solar radii. The polar plumes
are clearly distinguishable in both H I Ly-alpha and O VI. These
measurements were made in coordination with time resolved magnetograms
by the Michelson Doppler Imager (MDI) and time resolved XUV images
by the Extreme-Ultraviolet Imaging Telescope (EIT). This work is
supported by NASA Contract NAS5-31250 to the Smithsonian Astrophysical
Observatory, by the Italian Space Agency and by Switzerland.
---------------------------------------------------------
Title: The Coronal Diagnostic Spectrometer for the Solar and
Heliospheric Observatory: experiment description and calibration.
Authors: Harrison, R. A.; Kent, B. J.; Sawyer, E. C.; Hollandt, J.;
Kuhne, M.; Paustian, W.; Wende, B.; Huber, M. C. E.
1996Metro..32..647H Altcode:
The Coronal Diagnostic Spectrometer (CDS) to be flown aboard the
ESA/NASA Solar and Heliospheric Observatory (SOHO) is designed
to probe the solar atmosphere through the detection of spectral
emission lines in the extreme ultraviolet (EUV) wavelength range
15 nm to 80 nm. By observing the absolute and relative radiance of
selected lines and line profiles, one is able to derive temperature,
density, flow and abundance information for the plasmas in the solar
atmosphere. Spatial and temporal resolutions of down to a few arcseconds
and 1 second, respectively, allow such studies to be made within
the fine-scale structure of the solar corona. Simultaneous coverage
of large-wavelength bands provides the capability for simultaneously
observing the properties of plasmas across the wide temperature ranges
of the solar atmosphere. The pre-launch calibration is achieved through
the use of a hollow cathode discharge source which is used as a transfer
standard to allow calibration of the CDS against the primary standard
of the BESSY electron storage ring. By the use of different selected
gases in the discharge tube, each of the detector wavelength intervals
in the CDS can be covered adequately. The pre-delivery calibration of
the CDS has been performed and some results are shown.
---------------------------------------------------------
Title: First Results from the SOHO Ultraviolet Coronagraph
Spectrometer
Authors: Kohl, J. L.; Noci, G.; Antonucci, E.; Tondello, G.; Huber,
M. C. E.; Benna, C.; Ciaravella, A.; Fineschi, S.; Gardner, L. D.;
Giordano, S.; Karovska, M.; Michels, J.; Naletto, G.; Nicolosi, P.;
Poletto, G.; Pernechele, C.; Raymond, J. C.; Romoli, M.; Siegmund,
O. H. W.; Spadaro, D.; Smith, P. L.; Strachan, L.
1996AAS...188.4906K Altcode: 1996BAAS...28R.897K
The SOHO Ultraviolet Coronagraph Spectrometer (UVCS/SOHO) is being used
to observe the extended solar corona from 1.25 to 10 R_⊙ from Sun
center. Initial observations of polar coronal holes, polar plumes,
equatorial streamers and the diffuse mid-latitude corona will be
presented. The observations include measurements of spectral line
profiles for HI Lyman alpha and beta, and O VI 103.2 and 103.7
nm. Line intensities for Mg X 61.0 nm, Si XII 49.9 and 52.0 nm,
S X 119.6 nm, Fe XII 124.2 nm and several other minor ions have been
observed. Observations with moderate time resolution (about 1 minute) at
one strip of the corona will also be presented. Preliminary results for
derived proton and O VI velocity distributions and initial indications
of outflow velocities for protons, and O VI will be discussed as
well as preliminary results for other spectroscopic diagnostics
techniques. This research is supported by NASA Contract NAS5-31250 to
the Smithsonian Astrophysical Observatory, by the Italian Space Agency
and by Switzerland.
---------------------------------------------------------
Title: Coronal Emission Lines with UVCS
Authors: Raymond, J. C.; Noci, G.; Kohl, J. L.; Antonucci, E.;
Tondello, G.; Huber, M. C. E.; Benna, C.; Ciaravella, A.; Fineschi, S.;
Gardner, L. D.; Giordano, S.; Naletto, G.; Nicolosi, P.; Romoli, M.;
Siegmund, O. H. W.; Spadaro, D.; Smith, P. L.; Strachan, L.; Martin, R.
1996AAS...188.3702R Altcode: 1996BAAS...28Q.877R
The Ultraviolet Coronagraph Spectrometer aboard the SOHO satellite has
observed the extended solar corona in H I Lyalpha and O VI lines for
coronal diagnostics, but other, fainter, lines are also present. We
discuss a spectral atlas obtained from emission in equatorial streamers
and above solar active regions, pointing out lines which are especially
useful for determining the elemental abundances, ionization state,
and density of the emitting plasma. This work is supported by NASA
under contract NAS5-31250 to the Smithsonian Astrophysical Observatory.
---------------------------------------------------------
Title: Intercalibration and Co-Registration of the LASCO, UVCS and
SUMER instruments on SOHO
Authors: Michels, J.; Kohl, J. L.; Noci, G.; Antonucci, E.; Tondello,
G.; Huber, M. C. E.; Curdt, W.; Hollandt, J.; Lemaire, P.; Schuhle,
U.; Wilhelm, K.; Korendyke, C.; Moran, T.; Raymond, J. C.; Romoli,
M.; Benna, C.; Ciaravella, A.; Fineschi, S.; Gardner, L. D.; Giordano,
S.; Naletto, G.; Nicolosi, P.; Siegmund, O. H. W.; Spadaro, D.; Smith,
P. L.; Strachan, L.
1996AAS...188.3706M Altcode: 1996BAAS...28..878M
Joint observations of equatorial streamers by three SOHO instruments
have been used for radiometric intercalibration, co-registration and
other spectroscopic comparisons. The results are used to track the
stability of the radiometric calibrations of the Ultraviolet Coronagraph
Spectrometer (UVCS) and the Solar Ultraviolet Measurements of Emitted
Radiation (SUMER) experiment at overlapping wavelenghs. Observations
of equatorial streamers at heliocentric heights from 1.25 to 1.5
R_⊙ are used for the intercalibrations. The results are compared to
pre-launch laboratory calibrations and to observations of stars. The
first stellar observation was for 38 AQI. These UV observations are
compared to coronal green line (Fe XIV) observations obtained with the
Large Angle Spectrometric Coronagraph (LASCO) C1 coronagraph obtained
in the same time frame. Intercomparisons of spectral line profiles
among LASCO, SUMER, and UVCS are also planned. The LASCO research is
supported by NASA Grant NDPR S92835D; the UVCS research is supported by
NASA Contract NAS5-31250 to the Smithsonian Astrophysical Observatory,
by the Italian Space Agency and by Switzerland, and SUMER is financially
supported by BMFT/DARA, CNES, NASA and PRODEX (Swiss Contribution).
---------------------------------------------------------
Title: Future solar and Heliospheric ESA missions
Authors: Huber, M. C. E.
1996AdSpR..17d.355H Altcode: 1996AdSpR..17..355H
The status of solar mission preparation and planning within ESA
is summarised. The forthcoming far-reaching solar investigations
by the SOHO mission which, together with the CLUSTER space-plasma
physics mission, forms the first Cornerstone of `Horizon 2000' will
play a central role in the Agency's programme in the second half
of the 1990's. It is pointed out that a solar mission - probably
as an international collaboration - is part of the long-term plan
`Horizon 2000 Plus', whose implementation will be discussed at the
ESA Ministerial Meeting in Autumn 1995.
---------------------------------------------------------
Title: Source standards for the radiometric calibration of
astronomical telescopes in the VUV spectral range.
Authors: Hollandt, J.; Kuehne, M.; Huber, M. C. E.; Wende, B.
1996A&AS..115..561H Altcode:
On the basis of a high-current hollow-cathode discharge we have
developed two transfer source standards suitable for the radiometric
calibration of vacuum ultraviolet (VUV) telescopes. The source standards
are transportable and (in their current design) produce a collimated
beam of 5 and 10mm diameter. By irradiating the entrance aperture of
the telescope with this beam, the overall spectral response of the
instrument can be determined and spectral responsivity variations
over the entrance aperture can be directly evaluated. The transfer
standards described in this paper have been calibrated in the radiometry
laboratory of the Physikalisch-Technische Bundesanstalt (PTB) by use
of the calculable spectral photon flux of the Berlin electron storage
ring for synchrotron radiation BESSY - a primary radiometric VUV source
standard. The output of the source standards has been determined in 57
emission lines covering the wavelength range 15 to 150nm. The photon
flux in these emission lines ranges from 10^4^ to 10^9^s^-1^ and the
overall uncertainty of the photon flux in any given line is found to
be not more than 8% (1 sigma value).
---------------------------------------------------------
Title: The Coronal Diagnostic Spectrometer for the Solar and
Heliospheric Observatory: experiment description and calibration
Authors: Harrison, R. A.; Kent, B. J.; Sawyer, E. C.; Hollandt, J.;
K Hne, M.; Paustian, W.; Wende, B.; Huber, M. C. E.
1995Metro..32..647H Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The Coronal Diagnostic Spectrometer for the Solar and
Heliospheric Observatory
Authors: Harrison, R. A.; Sawyer, E. C.; Carter, M. K.; Cruise,
A. M.; Cutler, R. M.; Fludra, A.; Hayes, R. W.; Kent, B. J.; Lang,
J.; Parker, D. J.; Payne, J.; Pike, C. D.; Peskett, S. C.; Richards,
A. G.; Gulhane, J. L.; Norman, K.; Breeveld, A. A.; Breeveld, E. R.; Al
Janabi, K. F.; Mccalden, A. J.; Parkinson, J. H.; Self, D. G.; Thomas,
P. D.; Poland, A. I.; Thomas, R. J.; Thompson, W. T.; Kjeldseth-Moe,
O.; Brekke, P.; Karud, J.; Maltby, P.; Aschenbach, B.; Bräuninger,
H.; Kühne, M.; Hollandt, J.; Siegmund, O. H. W.; Huber, M. C. E.;
Gabriel, A. H.; Mason, H. E.; Bromage, B. J. I.
1995SoPh..162..233H Altcode:
The Coronal Diagnostic Spectrometer is designed to probe the solar
atmosphere through the detection of spectral emission lines in the
extreme ultraviolet wavelength range 150 - 800 å. By observing
the intensities of selected lines and line profiles, we may derive
temperature, density, flow and abundance information for the plasmas
in the solar atmosphere. Spatial and temporal resolutions of down to
a few arcseconds and seconds, respectively, allow such studies to be
made within the fine-scale structure of the solar corona. Futhermore,
coverage of large wavelength bands provides the capability for
simultaneously observing the properties of plasmas across the wide
temperature ranges of the solar atmosphere.
---------------------------------------------------------
Title: SUMER - Solar Ultraviolet Measurements of Emitted Radiation
Authors: Wilhelm, K.; Curdt, W.; Marsch, E.; Schühle, U.; Lemaire,
P.; Gabriel, A.; Vial, J. -C.; Grewing, M.; Huber, M. C. E.; Jordan,
S. D.; Poland, A. I.; Thomas, R. J.; Kühne, M.; Timothy, J. G.;
Hassler, D. M.; Siegmund, O. H. W.
1995SoPh..162..189W Altcode:
The instrument SUMER - Solar Ultraviolet Measurements of Emitted
Radiation is designed to investigate structures and associated dynamical
processes occurring in the solar atmosphere, from the chromosphere
through the transition region to the inner corona, over a temperature
range from 10<SUP>4</SUP> to 2 × 10<SUP>6</SUP>K and above. These
observations will permit detailed spectroscopic diagnostics of plasma
densities and temperatures in many solar features, and will support
penetrating studies of underlying physical processes, including plasma
flows, turbulence and wave motions, diffusion transport processes,
events associated with solar magnetic activity, atmospheric heating,
and solar wind acceleration in the inner corona. Specifically, SUMER
will measure profiles and intensities of EUV lines; determine Doppler
shifts and line broadenings with high accuracy; provide stigmatic
images of the Sun in the EUV with high spatial, spectral, and temporal
resolution; and obtain monochromatic maps of the full Sun and the inner
corona or selected areas thereof. SUMER will be flown on the Solar
and Heliospheric Observatory (SOHO), scheduled for launch in November,
1995. This paper has been written to familiarize solar physicists with
SUMER and to demonstrate some command procedures for achieving certain
scientific observations.
---------------------------------------------------------
Title: The Ultraviolet Coronagraph Spectrometer for the Solar and
Heliospheric Observatory
Authors: Kohl, J. L.; Esser, R.; Gardner, L. D.; Habbal, S.; Daigneau,
P. S.; Dennis, E. F.; Nystrom, G. U.; Panasyuk, A.; Raymond, J. C.;
Smith, P. L.; Strachan, L.; Van Ballegooijen, A. A.; Noci, G.;
Fineschi, S.; Romoli, M.; Ciaravella, A.; Modigliani, A.; Huber,
M. C. E.; Antonucci, E.; Benna, C.; Giordano, S.; Tondello, G.;
Nicolosi, P.; Naletto, G.; Pernechele, C.; Spadaro, D.; Poletto, G.;
Livi, S.; Von Der Lühe, O.; Geiss, J.; Timothy, J. G.; Gloeckler,
G.; Allegra, A.; Basile, G.; Brusa, R.; Wood, B.; Siegmund, O. H. W.;
Fowler, W.; Fisher, R.; Jhabvala, M.
1995SoPh..162..313K Altcode:
The SOHO Ultraviolet Coronagraph Spectrometer (UVCS/SOHO) is composed of
three reflecting telescopes with external and internal occultation and
a spectrometer assembly consisting of two toric grating spectrometers
and a visible light polarimeter. The purpose of the UVCS instrument is
to provide a body of data that can be used to address a broad range
of scientific questions regarding the nature of the solar corona and
the generation of the solar wind. The primary scientific goals are
the following: to locate and characterize the coronal source regions
of the solar wind, to identify and understand the dominant physical
processes that accelerate the solar wind, to understand how the coronal
plasma is heated in solar wind acceleration regions, and to increase the
knowledge of coronal phenomena that control the physical properties of
the solar wind as determined byin situ measurements. To progress toward
these goals, the UVCS will perform ultraviolet spectroscopy and visible
polarimetry to be combined with plasma diagnostic analysis techniques
to provide detailed empirical descriptions of the extended solar corona
from the coronal base to a heliocentric height of 12 solar radii.
---------------------------------------------------------
Title: The 29th ESLAB Symposium: opening address
Authors: Huber, Martin C. E.
1995Ap&SS.231D..13H Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Determining coronal electron temperatures from observations
with UVCS/SOHO
Authors: Fineschi, S.; Esser, R.; Habbal, S. R.; Karovska, M.; Romoli,
M.; Strachan, L.; Kohl, J. L.; Huber, M. C. E.
1995sowi.confQ..68F Altcode:
The electron temperature is a fundamental physical parameter of the
coronal plasma. Currently, there are no direct measurements of this
quantity in the extended corona. Observations with the Ultraviolet
Coronagraph Spectrometer (UVCS) aboard the upcoming Solar and
Heliospheric Observatory (SOHO) mission can provide the most direct
determination of the electron kinetic temperature (or, more precisely,
the electron velocity distribution along the line of sight). This
measurement is based on the observation of the Thomson-scattered Lyman
alpha (Ly-alpha) profile. This observation is made particularly
challenging by the fact that the integrated intensity of the
electron-scattered Ly-alpha line is about 10<SUP>3</SUP> times fainter
than that of the resonantly-scattered Ly-alpha component. In addition,
the former is distributed across 50 A (FWHM), unlike the latter that
is concentrated in 1 A. These facts impose stringent requirements on
the stray-light rejection properties of the coronagraph/spectrometer,
and in particular on the requirements for the grating. We make use of
laboratory measurements of the UVCS Ly-alpha grating stray-light, and of
simulated electron-scattered Ly-alpha profiles to estimate the expected
confidence levels of electron temperature determination. Models of
different structures typical of the corona (e.g., streamers, coronal
holes) are used for this parameter study.
---------------------------------------------------------
Title: Report on the activities of space science department,
mid 1992-1994
Authors: Huber, M. C. E.; Taylor, B. G.; Wenzel, K. -P.; Burke, W. R.
1995ESASP1179.....H Altcode: 1995rass.book.....H
No abstract at ADS
---------------------------------------------------------
Title: Opening remarks
Authors: Huber, Martin C. E.
1995SSRv...72....1H Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The Ultraviolet Coronagraph Spectrometer for the Solar and
Hellospheric Observatory
Authors: Raymond, J. C.; Kohl, J. L.; Esser, R.; Gardner, L. D.;
Habbal, S.; Strachan, L.; van Ballegooijen, A. A.; Noci, G.; Fineschi,
S.; Romoli, M.; Huber, M. C. E.; Antonucci, E.; Benna, C.; von der
Luhe, O.; Naletto, G.; Nicolosi, P.; Pernechele, C.; Tondello, G.;
Geiss, J.; Gloeckler, G.; Spadaro, D.; Daigneau, P. S.; Nystrom,
G. U.; Allegra, A.; Basile, G.; Brusa, R.; Wood, B.; Siegmund, O. H. W.
1995SPD....26..720R Altcode: 1995BAAS...27..970R
No abstract at ADS
---------------------------------------------------------
Title: Sun and - Challenges for Solar-Terrestrial Physics, - and
Hydrodynamics: Introduction
Authors: Huber, M. C. E.; Pedersen, A.; Frölich, C.
1995HiA....10..291H Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The Ultraviolet Coronagraph Spectrometer
Authors: Noci, G.; Kohl, J. L.; Huber, M. C. E.; Antonucci, E.;
Fineschi, S.; Gardner, L. D.; Naletto, G.; Nicolosi, P.; Raymond,
J. C.; Romoli, M.; Spadaro, D.; Strachan, L.; Tondello, G.; van
Ballegooijen, A.
1995LNP...444..261N Altcode: 1995cmer.conf..261N
The Ultraviolet Coronagraph Spectrometer (UVCS) is an instrument onboard
the Solar and Heliospheric (SOHO) spacecraft, a joint ESA/NASA mission
to be launched in 1995. The UVCS will provide ultraviolet spectroscopic
measurements to determine the primary plasma parameters of the solar
corona (temperatures, densities, velocities), from its base to as high
as 10 R<SUB>⊙</SUB>. We review briefly, here, its science objectives
and give an instrument description.
---------------------------------------------------------
Title: UVCS Science from SOHO
Authors: Antonucci, E.; Kohl, J. L.; Noci, G.; Huber, M. C. E.;
Fineschi, S.; Gardner, L. D.; Naletto, G.; Nicolosi, P.; Pernechele,
C.; Raymond, J. C.; Romoli, M.; Spadaro, Daniele; Strachan, L.;
Tondello, G.; van Ballegooijen, A.
1995jena.conf...80A Altcode:
The ultraviolet Coronagraph Spectrometer (UVCS), to be launched on
board SOHO in 1995, has been designed to determine the primary plasma
parameters in order to obtain a far more complete description of the
coronal plasma than presently exists. This will be accomplished by
obtaining ultraviolet spectroscopic observations in some EUV lines (HI
Ly Alpha, O VI, Mg X, Si XII, Fe XII) and in the visible continuum,
form the base of the solar corona to as high as 12 solar radii. The
profiles and intensities of the measured UV lines are sensitive
to effective temperature of protons, minor ions and electrons; ion
densities; chemical abundances; and outflow velocities of protons and
ions into the solar wind. The electron density is determined by means
of white light observations. The UVCS data will be used to address a
broad range of scientific questions concerning the nature of the solar
corona and the generation of the solar wind. The primary scientific
objectives are in fact those of identifying the source regions of the
slow and fast solar wind, understanding the dominant processes that
accelerate the solar wind, and the mechanisms for heating the coronal
plasma in the extended corona.
---------------------------------------------------------
Title: Opening Remarks
Authors: Huber, M. C. E.
1995hlh..conf....1H Altcode:
No abstract at ADS
---------------------------------------------------------
Title: UVCS/SOHO capability for determining coronal conditions before,
during and after CMEs
Authors: Strachan, L.; Raymond, J. C.; Kohl, J. L.; Noci, G.;
Antonucci, E.; Tondello, G.; Huber, M. C. E.; Fineschi, S.; Gardner,
L. D.; Nicolosi, P.; Romoli, M.
1994ESASP.373..421S Altcode: 1994soho....3..421S
No abstract at ADS
---------------------------------------------------------
Title: Results and experiences from Apollo and other Lunar missions.
Authors: Geiss, J.; Huber, M. C. E.
1994ESASP1170...15G Altcode: 1994luna.work...15G
No abstract at ADS
---------------------------------------------------------
Title: 'SUMER' - Solar Ultraviolet Measurements of Emitted Radiation
Authors: Wilhelm, K.; Curdt, W.; Gabriel, A. H.; Grewing, M.; Huber,
M. C. E.; Jordan, S. D.; Kuhne, M.; Lemaire, P.; Marsch, E.; Poland,
A. I.; Schuhle, U.; Thomas, R. J.; Timothy, J. G.; Vial, J. -C.
1994scs..conf..619W Altcode: 1994IAUCo.144..619W
SUMER is designed for the investigations of plasma flow characteristics,
turbulence and wave motions, plasma densities and temperatures,
structures and events associated with solar magnetic activity in the
chromosphere, the transition zone and the corona. The spatial and
spectral resolution capabilities of the instrument are considered in
some detail, and a new detector concept is introduced.
---------------------------------------------------------
Title: International lunar workshop : 'Towards a world strategy for
the exploration and utilisation of our natural satellite', Beatenberg
(Interlaken) Switzerland, 31 May-3 June 1994
Authors: Balsiger, H.; Huber, M. C. E.; Léna, Pierre
1994ESASP1170.....B Altcode: 1994twse.conf.....B
No abstract at ADS
---------------------------------------------------------
Title: Maintaining the Astronomical Environment for Space Astronomy
Authors: Huber, M. C. E.
1994ASSL..187..113H Altcode: 1994fsgb.book..113H
No abstract at ADS
---------------------------------------------------------
Title: SUMER - Solar Ultraviolet Measurements of Emitted Radiation
Authors: Wilhelm, K.; Curdt, W.; Marsch, E.; Schuehle, U.; Gabriel,
A. H.; Lemaire, P.; Vial, J. -C.; Grewing, M.; Huber, M. C. E.;
Jordan, S. D.; Poland, A. I.; Thomas, R. J.; Kuehne, M.; Timothy, J. G.
1993BAAS...25.1192W Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Ti-ii transition probabilities and radiative lifetimes in TI
and the solar titanium abundance
Authors: Bizzarri, A.; Huber, M. C. E.; Noels, A.; Grevesse, N.;
Bergeson, S. D.; Tsekeris, P.; Lawler, J. E.
1993A&A...273..707B Altcode:
Transition probabilities of 100 Ti-II emission lines, originating
from 7 different atomic levels, have been determined by combining
branching fractions with radiative lifetimes. The branching fractions
were measured using Fourier transform spectroscopy on a hollow
cathode. The radiative lifetimes of these 7 - and 35 additional -
levels were measured using time resolved laser-induced fluorescence
on a slow Ti ion beam. <P />The transition probabilities of 21 very
weak lines have been used to derive a solar titanium abundance of
α<SUB>Ti</SUB> = log(N<SUB>Ti</SUB>/N<SUB>H</SUB>) + 12=5.04±0.04 dex,
which is insensitive to the solar model. This value is in disagreement
with the meteoritic titanium abundance (4.93±0.02).
---------------------------------------------------------
Title: The High Resolution Extreme-Ultraviolet Spectroheliometer
(HiRES) Experiment: Capabilities and Observing Goals
Authors: Berger, T. E.; Timothy, J. G.; Walker, A. B. C., Jr.; Jain,
S. K.; Saxena, A. K.; Bhattacharyya, J. C.; Huber, M. C. E.; Tondello,
G.; Naletto, G.
1993BAAS...25.1209B Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Solar physics within ESA's planning.
Authors: Huber, M. C. E.
1993ESASP1157...81H Altcode: 1993srfs.book...81H
A summary of the necessary (but not sufficient) steps involved in
planning "solar physics from space" is presented.
---------------------------------------------------------
Title: HiRES: High Resolution Extreme Ultraviolet Spectroheliometer.
Authors: Berger, T.; Bergamini, P.; Kirby, H.; Timothy, J. G.; Walker,
A. B. C.; Bhattacharyya, J. C.; Jain, S. K.; Saxena, A. K.; Huber,
M. C. E.; Naletto, G.; Tondello, G.
1993uxrs.conf..289B Altcode: 1993uxsa.conf..289B
The HiRES sounding rocket payload is designed to obtain very high
spatial, spectral, and temporal resolution images of the solar
chromospheric and coronal plasmas in the extreme ultraviolet (EUV)
wavelength range from 500 to 650 Å. The instrument consists of a 450
mm f/15 Gregorian telescope feeding a 1-m normal incidence stigmatic
spectrometer. The stigmatic spectrometer utilizes a toroidal diffraction
grating formed by a unique elastic substrate deformation technique
in order to achieve simultaneous spatial and spectral focusing at
two points on the detector plane. Spatial resolution on the order
of 0.4 arcsecond across a 3×3 arcmin<SUP>2</SUP> field of view is
obtained. Temporal resolution of the order of milliseconds is achieved
by the use of an advanced imaging Multi-Anode Microchannel Array
(MAMA) detector. A hydrogen-alpha 6562.8 Å camera and a 0.25-m EUV
solar irradiance spectrometer are also included in the payload.
---------------------------------------------------------
Title: Hollow Cathode Transfer Standards for the Radiometric
Calibration of VUV Telescopes of the Solar and Heliospheric
Observatory (SOHO)
Authors: Hollandt, J.; Huber, M. C. E.; Kühne, M.
1993Metro..30..381H Altcode:
On board the ESA/NASA space mission SOHO (Solar and Heliospheric
Observatory) there will be several VUV telescope/spectrometer systems
to observe the solar disk and its corona in the wavelength range 15
nm to 160 nm. To determine the absolute spectral sensitivity of these
instruments prior to launching, transfer source standards have been
developed. These transfer standards consist of a high-current hollow
cathode source combined with collimating optics. One standard uses a
concave mirror at normal incidence for the wavelength range 50 nm to
160 nm and the other standard uses Wolter type II grazing incidence
optics for the range 16 nm to 80 nm. These transfer source standards
are calibrated against the electron storage ring BESSY as a primary
radiometric source standard.
---------------------------------------------------------
Title: Report on the activities of the Space Science Department,
1990 - Mid 1992
Authors: Huber, M. C. E.; Pedersen, A.; Taylor, B. G.; Wenzel, K. -P.
1993ESASP1161.....H Altcode: 1993rass.book.....H
No abstract at ADS
---------------------------------------------------------
Title: An imaging extreme ultraviolet spectrometer.
Authors: Bergamini, P.; Berger, T. E.; Giaretta, G.; Huber, M. C. E.;
Naletto, G.; Timothy, J. G.; Tondello, G.
1993uxrs.conf..285B Altcode: 1993uxsa.conf..285B
A laboratory extreme ultraviolet (EUV) imaging spectrometer has
been fabricated and tested. This instrument is used to test and to
characterize toroidal gratings like those which will be employed in
the high-resolution spectroheliometer (HiRES) configured for flight
on a sounding rocket. The imaging spectrometer will be used also for
characterization and calibration of Multi Anode Microchannel Array
(MAMA) detectors foreseen on the ESA/NASA Solar Heliospheric Observatory
(SOHO) satellite. The spectrometer employs a concave toroidal grating
illuminated at normal incidence in a 1 meter Rowland circle mounting:
high efficiency is achieved because the grating is the only reflecting
surface. The grating is able to produce stigmatic images over
a wavelength range of about 100 Å or 200 Å centered respectively
around 600 Å or 1200 Å. The results of the initial imaging tests
and the measurements carried out are presented and discussed.
---------------------------------------------------------
Title: Some European activities in support of the SOHO mission.
Authors: Huber, Martin C. E.; Domingo, Vicente
1992ESASP.348..393H Altcode: 1992cscl.work..393H
The rationale and potential functions of the European Science Data
and Operations Centre (ESDOC) are outlined. Other efforts, namely
the gathering of support - through the Joint Organisation for Solar
Observations (JOSO) - for ground-based observations in the context of
the SOHO mission, as well as the development of a vacuum-ultraviolet
(VUV) transfer source standard - to be used for radiometrically
intercomparing spectrometric SOHO instruments - are also described.
---------------------------------------------------------
Title: SUMER: temperatures, densities, and velocities in the outer
solar atmosphere.
Authors: Lemaire, P.; Wilhelm, K.; Axford, W. I.; Curdt, W.; Gabriel,
A. H.; Grewing, M.; Huber, M. C. E.; Jordan, S. D.; Kuehne, M.;
Marsch, E.; Poland, A. I.; Richter, A. K.; Thomas, R. J.; Timothy,
J. G.; Vial, J. C.
1992ESASP.348...13L Altcode: 1992cscl.work...13L
The SUMER instrumentation, that will be mounted on the SOHO spacecraft,
is in development under MPAE leadership. It has some capability
to improve the solar angular resolution and the spectral resolution
already obtained in the far UV to the extreme UV, corresponding to the
temperature range between 10<SUP>4</SUP> and a few 10<SUP>6</SUP>K. The
authors give some insights into the SUMER spectrometer that is developed
to study the dynamics and to infer temperatures and densities of the
low corona and the chromosphere-corona transition zone in using the
50 - 160 nm wavelength range. First, they recall the SUMER scientific
goals and the technics used. Then, after a brief description of the
instrumentation the expected performances are described. The way the
observations can be conducted is emphasized and it is shown how SUMER
is operated in coordination with other SOHO instrumentations and in
cooperation with ground-based observations.
---------------------------------------------------------
Title: "SUMER" - Solar Ultraviolet Measurements of Emitted Radiation.
Authors: Wilhelm, K.; Axford, W. I.; Curdt, W.; Gabriel, A. H.;
Grewing, M.; Huber, M. C. E.; Jordan, S. D.; Kühne, M.; Lemaire, P.;
Marsch, E.; Poland, A. I.; Richter, A. K.; Thomas, R. J.; Timothy,
J. G.; Vial, J. C.
1992eocm.rept..225W Altcode:
The experiment Solar Ultraviolet Measurements of Emitted Radiation
(SUMER) is designed for the investigations of plasma flow
characteristics, turbulence and wave motions, plasma densities
and temperatures, structures and events associated with solar
magnetic activity in the chromosphere, the transition zone and the
corona. Specifically, SUMER will measure profiles and intensities
of extreme ultraviolet (EUV) lines emitted in the solar atmosphere
ranging from the upper chromosphere to the lower corona; determine line
broadenings, spectral positions and Doppler shifts with high accuracy;
provide stigmatic images of selected areas of the Sun in the EUV with
high spatial, temporal and spectral resolution and obtain full images of
the Sun and the inner corona in selectable EUV lines, corresponding to a
temperature range from 10<SUP>4</SUP> to more than 1.8×10<SUP>6</SUP>K.
---------------------------------------------------------
Title: Radiometric calibration of solar space telescopes - The
development of a vacuum-ultraviolet transfer source standard
Authors: Hollandt, J.; Kuehne, M.; Huber, M. C. E.
1992ESABu..69...79H Altcode:
The development of a source standard for the vacuum-ultraviolet
spectral region will facilitate the laboratory calibration and
radiometric intercomparison of the coronal telescopes to be flown on
ESA's Solar and Heliospheric Observatory (SOHO) spacecraft. Perhaps
surprisingly, the sun's output in this spectral region is not
well known, because variations in the output itself, and those
due to the instrument-sensitivity and radiometric-calibration
uncertainties of earlier space telescopes, could not be satisfactorily
resolved. Radiometric intercomparison of SOHO's instruments on the
ground, strict attention to cleanliness, and in-orbit intercomparisons
are providing the means for vastly improved solar radiometry, which
is of interest not only to astrophysicists but also to aeronomists.
---------------------------------------------------------
Title: Radiometric calibration of solar space telescopes - the
development of a vacuum-ultraviolet transfer source standard.
Authors: Hollandt, J.; Kühne, M.; Huber, M. C. E.
1992ESABu..69...78H Altcode:
The development of a source standard for the vacuum-ultraviolet
spectral region will facilitate the laboratory calibration and
radiometric intercomparison of the coronal telescopes to be flown on
ESA's Solar and Heliospheric Observatory (Soho) spacecraft. Radiometric
intercomparison of Soho's instruments on the ground, strict attention
to cleanliness, and in-orbit intercomparisons are providing the means
for vastly improved solar radiometry.
---------------------------------------------------------
Title: SUMER - Solar ultraviolet measurements of emitted radiation
Authors: Wilhelm, K.; Axford, W. I.; Gurdt, W.; Marsch, E.; Richter,
A. K.; Grewing, M.; Gabriel, A. H.; Lemaire, P.; Vial, J. -C.; Huber,
M. C. E.
1992sws..coll..129W Altcode:
The SUMER (solar ultraviolet measurements of emitted radiation)
experiment is described. It will study flows, turbulent motions, waves,
temperatures and densities of the plasma in the upper atmosphere of
the Sun. Structures and events associated with solar magnetic activity
will be observed on various spatial and temporal scales. This will
contribute to the understanding of coronal heating processes and the
solar wind expansion. The instrument will take images of the Sun in EUV
(extreme ultraviolet) light with high resolution in space, wavelength
and time. The spatial resolution and spectral resolving power of the
instrument are described. Spectral shifts can be determined with
subpixel accuracy. The wavelength range extends from 500 to 1600
angstroms. The integration time can be as short as one second. Line
profiles, shifts and broadenings are studied. Ratios of temperature
and density sensitive EUV emission lines are established.
---------------------------------------------------------
Title: Design and test of a High-Resolution EUV Spectroheliometer
Authors: Berger, Thomas E.; Timothy, J. G.; Walker, Arthur B. C., Jr.;
Kirby, Helen; Morgan, Jeffrey S.; Jain, Surendra K.; Saxena, Ajay K.;
Bhattacharyya, Jagadish C.; Huber, Martin C. E.; Tondello, Giuseppe
1992SPIE.1546..446B Altcode: 1992SPIE.2011..446B
The HiRES High-Resolution EUV Spectroheliometer is a sounding rocket
instrument yielding very high spatial, spectral, and temporal resolution
images of the solar outer atmosphere, on the basis of a 45-cm Gregorian
telescope feeding a normal-incidence stigmatic EUV spectrometer with
imaging multianode microchannel-array detector system, as well as an
IR spectrometer with imaging CCD detector system. Attention is given
to the expected performance of this system, including the effects of
vibrational misalignments due to the sounding rocket flight environment.
---------------------------------------------------------
Title: Fabrication of toroidal and coma-corrected toroidal diffraction
gratings from spherical master gratings using elastically deformable
substrates: a progress report
Authors: Huber, Martin C. E.; Timothy, J. G.; Morgan, Jeffrey S.;
Lemaitre, Gerard; Tondello, Giuseppe; Naletto, Giampiero
1991SPIE.1494..472H Altcode:
A technique has been developed that permits toroidal, and coma-corrected
toroidal, diffraction gratings to be replicated from spherical master
gratings with the use of elastically-deformable substrates. Toroidal
gratings correct astigmatism and, thus make it possible to
construct stigmatic spectrometers that employ a single reflective
diffraction grating. These spectrometers are particularly useful
for the extreme-ultraviolet (EUV) wavelength range, where reflection
coefficients are low, since the single optical surface provides for
dispersion, focusing, and astigmatism correction. The fabrication
procedures for the pure toroidal, and coma-corrected toroidal,
gratings are described, and initial test results are presented. The
use of the toroidal gratings in a high-resolution sounding-rocket
EUV spectroheliometer (HiRES), and in both the coronal diagnostics
spectrometer (CDS) and the ultraviolet coronagraph spectrometer (UVCS)
on the ESA/NASA Solar and Heliospheric Observatory (SOHO) mission, is
described briefly, and the use of this technique for the fabrication
of a coma-corrected toroidal grating for the prime Rowland spectrograph
of the FUSE/Lyman mission is discussed.
---------------------------------------------------------
Title: HiRES: a high-resolution stigmatic extreme ultraviolet
spectroheliometer for sudies of the fine-scale structure of the
solar chromosphere, transition region, and corona.
Authors: Timothy, J. G.; Berger, Thomas E.; Morgan, Jeffrey S.;
Walker, Arthur B. C., Jr.; Jain, Surendra K.; Saxena, Ajay K.;
Bhattacharyya, Jagadish C.; Huber, Martin C. E.; Tondello, Giuseppe;
Naletto, Giampiero
1991OptEn..30.1142T Altcode:
The authors describe the design of a high-resolution stigmatic
extreme-ultraviolet spectroheliometer, which consists of a 45 cm
Gregory telescope coupled to a spectrometer employing a single toroidal
diffraction grating in a normal-incidence Rowland circle mounting and
an imaging pulse-counting multianode microchannel array (MAMA) detector
system. The spectroheliometer will produce spatially resolved spectra
of the chromosphere, transition region, and corona with an angular
resolution of 0.4″or better, a spectral resolution λ/Δλ of about
10<SUP>4</SUP> in first order, and a temporal resolution of the order
of seconds. Because of the geometric fidelity of the MAMA detector
system, the spectroheliometer will be able to determine Doppler shifts
to a resolution of at least 2 mÅ at wavelengths near 600Å (≡1.0
km s<SUP>-1</SUP>), depending on the level of the accumulated signal.
---------------------------------------------------------
Title: Comet Nucleus Sample Return - Plans and Capabilities
Authors: Huber, M. C. E.; Schwehm, G.
1991SSRv...56..109H Altcode:
ROSETTA — the Comet Nucleus Sample Return mission — is one of the
four Cornerstone missions to which ESA has committed itself in its
approved Long-Term Programme Horizon 2000. The mission is currently
being studied in collaboration with NASA. The comet-nucleus samples
that ROSETTA is to provide will allow us to study some of the most
primitive material in the solar system and the physical and chemical
processes that marked the beginning of the system 4.6 billion years
ago. For ESA, ROSETTA is a new type of mission: one which will return
a sample at cryogenic temperature, and where as much effort has to
be spent on preparing the laboratory analysis on-ground as has to be
invested in preparing the space segment with the sample acquisition
and in situ documentation. As part of the preparation for this mission,
ESA is now starting to consider Planetary Protection issues.
---------------------------------------------------------
Title: In-Orbit Extreme Ultraviolet Radiometric Calibration of
Satellite Instrumentation
Authors: Smith, P. L.; Huber, M. C. E.; Parkinson, W. H.; Kuhne, M.;
Kock, M.
1991eua..coll..390S Altcode:
No abstract at ADS
---------------------------------------------------------
Title: UV observational techniques for the extended solar corona
Authors: Kohl, J. L.; Gardner, L. D.; Huber, M. C. E.; Nicolosi,
P.; Noci, G.; Naletto, G.; Romoli, M.; Spadaro, D.; Tondello, G.;
Weiser, H.
1991AdSpR..11a.359K Altcode: 1991AdSpR..11..359K
The SOHO Ultraviolet Coronagraph Spectrometer is being developed for
spectroscopic determinations of temperatures, densities and flow
velocities in the extended solar corona. Determinations of plasma
parameters for the primary particles (electrons and protons) and for
several minor ions are planned. The techniques and instrumentation
to be used must overcome the relatively low intensity levels and
potentially high stray light levels intrinsic to observations of the
extended corona while also providing high radiometric and spectrometric
accuracy and relatively high spectral and spatial resolution. This
paper concentrates on the instrument characteristics that are required
to observe the resonantly scatter HI Lyman-alpha line at heliocentric
heights from 1 to 10 solar radii.
---------------------------------------------------------
Title: Coronal observations with SOHO
Authors: Huber, Martin C. E.; von der Luehe, Oskar
1991AdSpR..11a.339H Altcode: 1991AdSpR..11..339H
The Solar and Heliospheric Observatory (SOHO) will carry a set of
solar physics experiments which permit a thorough investigation of
the solar corona. The emphasis of the mission is on the measurement
of the physical properties of coronal structures and the processes
occurring therein, leading - it is hoped - to an understanding of
the mechanism(s) by which the solar corona is heated and the solar
wind is accelerated. The observations will be made from a halo orbit
around the L1 Lagrange point on the Earth-Sun line and will range from
magnetic field measurements in the photosphere through spectroscopic
plasma diagnostics of chromospheric, transition-zone and coronal
structures with high spatial and spectral resolution, to coronagraphic
observations out to 30 solar radii and to mass spectrometry of the
solar wind near one astronomical unit. <P />SOHO is part of the Solar
Terrestrial Science Programme (STSP), the first `Cornerstone' in ESA's
long-term scientific programme `Space Science - Horizon 2000', and
will therefore be flown in connection with the other STSP component,
the four-spacecraft Cluster mission, which will investigate plasma
structures and processes in the magnetosphere in three dimensions. <P
/>Both STSP missions, i.e. SOHO and Cluster will address the physics of
plasma structures and processes, that are accessible to investigation
in the solar-terrestrial context, yet are thought to be examples of
plasma processes and structures that are ubiquitous in the cosmos. It
is hoped that a cross-fertilisation between the scientific communities
associated with SOHO and Cluster will take place, as they investigate
the physics of the coronal and magnetospheric plasma with complementary
methods and techniques - globally by remote observations, and in detail,
by multi-point in-situ measurements.
---------------------------------------------------------
Title: A High Efficiency Imaging Extreme Ultraviolet Spectrometer
Authors: Morgan, J. S.; Timothy, J. G.; Slater, D. C.; Huber, M. C. E.;
Tondello, G.; Jannitti, E.; Naletto, G.; Nicolosi, P.; Lemaitre, G.
1991eua..coll..380M Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Transition probabilities from the 6s6p
<SUP>1</SUP>P°<SUB>1</SUB> resonance level of neutral barium
Authors: Bizzarri, A.; Huber, M. C. E.
1990PhRvA..42.5422B Altcode:
From spectra of a very weak barium hollow-cathode discharge obtained
with a Fourier-transform spectrometer, the branching ratio between the
visible resonance line at 553.5 nm and the infrared line at 1500 nm of
the barium atom was determined to be 485+/-40. Given the known lifetime
and branching fractions between the infrared lines originating in the
resonance level, it is now possible to present definitive branching
fractions and transition probabilities for all transitions out of the
6s6p <SUP>1</SUP>P<SUP>°</SUP><SUB>1</SUB> barium resonance level.
---------------------------------------------------------
Title: Report on the activities of Space Science Department in 1988
- 1989.
Authors: Huber, M. C. E.; Pedersen, A.; Taylor, B. G.; Wenzel, K. -P.
1990roas.book.....H Altcode:
Contents: 1. Solar and Heliospheric Science Division. 2. Planetary
and Space Science Division. 3. Astrophysics Division. 4. Symposia
and workshops.
---------------------------------------------------------
Title: Activities report of the Space Science Department
Authors: Huber, M. C. E.; Pedersen, A.; Taylor, B. G.; Wenzel, K. -P.;
David, Valerie
1990esa..rept.1988H Altcode:
The research and development carried out is reported. Divisions covered
are solar and heliospheric science, planetary and space, astrophysics,
and symposia and workshops. The research and support to projects and
studies is reviewed. Research in astrophysics carried out in the EXOSAT
and IUE laboratories is reported.
---------------------------------------------------------
Title: Fe II transition probabilities and the solar iron abundance
Authors: Pauls, U.; Grevesse, N.; Huber, M. C. E.
1990A&A...231..536P Altcode:
Branching fractions for three near-infrared Fe II lines are presented
that fulfill the requirements necessary for an accurate solar
abundance determination. The lines belong to the dominant ionization
stage and are weak enough to lie on the linear part of the curve of
growth. The resulting abundance is insensitive to deviations from
local thermodynamic equilibrium and is independent of assumptions
concerning the temperature model and line-broadening parameters. From
the transition probabilities and from accurate solar equivalent widths,
a solar photospheric iron abundance is obtained.
---------------------------------------------------------
Title: General Discussion
Authors: Huber, M. C. E.
1990ebua.conf..263H Altcode:
No abstract at ADS
---------------------------------------------------------
Title: ESA Astronomical projects
Authors: Huber, M. C. E.
1990nwus.book..535H Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Opening Remarks
Authors: Huber, M. C. E.
1989ESASP.290D..12H Altcode: 1989isa..bookD..12H
No abstract at ADS
---------------------------------------------------------
Title: Transition probabilities for infrared and visible lines in
neutral barium
Authors: Niggli, S.; Huber, M. C. E.
1989PhRvA..39.3924N Altcode:
From narrow-band and broadband spectra of barium hollow-cathode
discharges obtained with the aid of a Fourier-transform spectrometer,
we have determined the branching fractions of five moderately excited
levels and the branching ratios between the infrared lines originating
in the resonance level 6s6p <SUP>1</SUP>°<SUB>1</SUB> of the neutral
barium atom. By combining our emission measurements with lifetime
and absorption data taken from the literature we were able to derive
transition probabilities for 13 visible and 16 infrared transitions
as well as upper limits for the A values of 15 additional infrared
lines. The resulting transition probabilities cover five decades.
---------------------------------------------------------
Title: SUMER - Solar ultraviolet measurements of emitted radiation.
Authors: Curdt, W.; Wilhelm, K.; Axford, W. I.; Marsch, E.; Richter,
A. K.; Gabriel, A. H.; Lemaire, P.; Vial, J. -C.; Grewing, M.; Huber,
M. C. E.; Jordan, S. D.; Poland, A. I.; Thomas, R. J.; Timothy, J. G.
1989AGAb....2...14C Altcode: 1989amt..conf...14C
No abstract at ADS
---------------------------------------------------------
Title: CDS: The Coronal Diagnostic Spectrometer
Authors: Patchett, B. E.; Harrison, R. A.; Sawyer, E. C.; Aschenbach,
B.; Culhane, J. L.; Doschek, G. A.; Gabriel, A. H.; Huber, M. C. E.;
Jordan, C.; Kjeldseth-Moe, O.
1988sohi.rept...39P Altcode:
The prime objective of the Coronal Diagnostic Spectrometer (CDS) is to
obtain intensity ratios of selected extreme-ultraviolet line pairs, with
spatial and temporal scales appropriate to the fine-scale features of
the solar atmosphere. This will be done simultaneously across a large
portion of the solar atmosphere. From this, density and temperature
information will be derived which coupled with a modest capability for
the detection of flows will be used to study the energy and mass balance
of the atmosphere. Understanding the heating of the solar corona and the
acceleration of the solar wind are the ultimate goals of this research.
---------------------------------------------------------
Title: SUMER: Solar Ultraviolet Measurements of Emitted Radiation
Authors: Wilhelm, K.; Axford, W. I.; Curdt, W.; Gabriel, A. H.;
Grewing, M.; Huber, M. C. E.; Jordan, M. C. E.; Lemaire, P.; Marsch,
E.; Poland, A. I.
1988sohi.rept...31W Altcode:
The SUMER (solar ultraviolet measurements of emitted radiation)
experiment is described. It will study flows, turbulent motions, waves,
temperatures and densities of the plasma in the upper atmosphere of
the Sun. Structures and events associated with solar magnetic activity
will be observed on various spatial and temporal scales. This will
contribute to the understanding of coronal heating processes and the
solar wind expansion. The instrument will take images of the Sun in EUV
(extreme ultra violet) light with high resolution in space, wavelength
and time. The spatial resolution and spectral resolving power of the
instrument are described. Spectral shifts can be determined with
subpixel accuracy. The wavelength range extends from 500 to 1600
angstroms. The integration time can be as short as one second. Line
profiles, shifts and broadenings are studied. Ratios of temperature
and density sensitive EUV emission lines are established.
---------------------------------------------------------
Title: Imaging extreme ultraviolet spectrometer employing a single
toroidal diffraction grating: the initial evaluation
Authors: Huber, M. C. E.; Timothy, John G.; Morgan, Jeffrey S.;
Lemaitre, G.; Tondello, Giuseppe; Jannitti, E.; Scarin, P.
1988ApOpt..27.3503H Altcode:
The design and test results of a high-efficiency EUV imaging
spectrometer employing a concave toroidal grating which is illuminated
at normal incidence in a Rowland circle mounting and has only one
reflecting surface are discussed. Photographic tests and initial
photoelectric tests with a two-dimensional pulse-counting detector
system demonstrate the excellent image quality of the grating at
wavelengths near 600 A. Applications of the spectrometer for the study
of nonsolar objects and solar regions (including the chromosphere,
transition region, and corona) are considered.
---------------------------------------------------------
Title: Report on the activites of the Space Science Department
Authors: Huber, M. C. E.; Pedersen, A.; Taylor, B. G.; Wenzel, K. -P.;
Kaldeich, Brigitte; Longdon, Norman
1988esa..rept.1986H Altcode:
Research in solar and heliospheric science; planetary and space science;
and astrophysics is summarized. Comets; planetary dust and plasma;
the magnetosphere; and the EXOSAT and IUE programs are discussed.
---------------------------------------------------------
Title: Precise Atomic Data
Authors: Huber, M. C. E.
1988IAUS..132..361H Altcode:
The author discusses the three questions: Why do we need accurate
atomic data for stellar spectroscopy? What accuracy is needed? And:
How can the accuracy of oscillator strengths be assessed? In conclusion
the author comments on the state of the art, stresses the importance of
uncertainty estimates and also discernes between precision and accuracy.
---------------------------------------------------------
Title: Evaluation of toroidal gratings in the EUV.
Authors: Huber, M. C. E.; Lemaître, G.; Naletto, G.; Nicolosi, P.;
Tondello, G.; Jannitti, E.; Morgan, J. S.; Timothy, J. G.
1988SPIE..982..372H Altcode: 1988xia..conf..372H
Toroidal gratings can be used for imaging spectrometers. These can
provide stigmatic images and are very useful for space applications. Two
cases are described: an Ultraviolet Coronagraph for the solar SOHO
mission and a high resolution spectrometer for the stellar Lyman
mission. The toroidal gratings have been produced by replicating an
elastically deformed spherical one. By properly applying the distorting
forces also coma-corrected surfaces can be achieved.
---------------------------------------------------------
Title: A Photospheric Solar Iron Abundance from Weak FeII Lines
Authors: Pauls, U.; Grevesse, N.; Huber, M. C. E.
1988IAUS..132..425P Altcode:
The high resolution and the high light-gathering power of a
Fourier-transform spectrometer afford the observation of very weak
lines in laboratory spectra. Thus it became possible to determine an
accurate solar iron abundance from Fe II lines that are weak in the
solar spectrum: the authors measured the branching fractions of a few
such lines whose upper levels lifetimes are known.
---------------------------------------------------------
Title: The Work of the ESO Observing Programmes Committee / Opc
Authors: Huber, M. C. E.
1988copa.conf..239H Altcode:
The scientific evaluation of applications for observing time at ESO's
La Silla Observatory is described. While one can certainly improve
on streamlining the co-ordination of observations, the question,
whether telescope time will be given, will always have to depend on
the scientific case that has been made - be it for multi-wavelength
or other co-ordinated observations or be it for more traditional
observations with a single telescope.
---------------------------------------------------------
Title: Absolute, extreme-ultraviolet, solar spectral irradiance
monitor (AESSIM)
Authors: Huber, Martin C. E.; Smith, Peter L.; Parkinson, W. H.;
Kuehne, M.; Kock, M.
1988AdSpR...8g..81H Altcode: 1988AdSpR...8...81H
AESSIM, the Absolute, Extreme-Ultraviolet, Solar Spectral Irradiance
Monitor, is designed to measure the absolute Solar spectral irradiance
at extreme-ultraviolet (EUV) wavelengths. The data are required for
studies of the processes that occur in the Earth's upper atmosphere
and for predictions of atmospheric drag on space vehicles. AESSIM is
comprised of Sun-pointed spectrometers and newly-developed, secondary
standards of spectral irradiance for the EUV. Use of the in-orbit
standard sources will eliminate the uncertainties caused by changes
in spectrometer efficiency that have plagued all previous measurements
of the Solar spectral EUV flux.
---------------------------------------------------------
Title: Absolute Extreme-Ultraviolet Solar Spectral Irradiance Monitor
Authors: Smith, Peter L.; Parkinson, W. H.; Kuhne, Michael; Huber,
Martin C. E.; Kock, Manfred
1988soae.conf..104S Altcode:
No abstract at ADS
---------------------------------------------------------
Title: A photospheric solar iron abundance from weak Fe II lines
Authors: Pauls, U.; Huber, M. C. E.; Grevesse, N.
1988ASSL..138...79P Altcode: 1988IAUCo..94...79P; 1988pffl.proc...79P
The main difficulties encountered in determining a photospheric solar
iron abundance are considered and a way is shown to circumvent most
of them. Branching fractions of weak Fe II lines are measured from a
hollow-cathode discharge to derive accurate transition probabilities
from a previously determined lifetime. These transition probabilities -
together with accurate equivalent widths from the solar spectrum - are
subsequently used to calculate a photospheric iron abundance. The choice
of suitable lines results in an abundance value nearly independent of
any assumption concerning the temperature model and line-broadening
parameters.
---------------------------------------------------------
Title: Absolute Oscillator Strengths for 108 Lines of SI i between
163 and 410 Nanometers
Authors: Smith, Peter L.; Huber, M. C. E.; Tozzi, G. P.; Griesinger,
H. E.; Cardon, B. L.; Lombardi, G. G.
1987ApJ...322..573S Altcode:
Measurements of neutral silicon oscillator strengths (f-values)
obtained by absorption and emission techniques have been combined
using the numerical procedure of Cardon et al. (1979) to produce 108
f-values for the Si I lines between 163 and 410 nm. Beam-foil-lifetime
measurements were employed to determine the absolute scale. The present
measurements have uncertainties of about 0.07 dex (+ or - 16 percent)
at the 1-sigma level of confidence. Good agreement is obtained between
the results and previous data. The data also provide upper limits for
the f-values of 22 other lines and information on the lifetimes for
36 levels in Si I.
---------------------------------------------------------
Title: Workshop 3: Solar-terrestrial physics
Authors: Huber, M. C. E.; et al.
1987ESASP.268..147H Altcode: 1987sass.conf..147H
No abstract at ADS
---------------------------------------------------------
Title: Transition probabilities in neutral barium
Authors: Niggli, S.; Huber, M. C. E.
1987PhRvA..35.2908N Altcode:
We present emission measurements on a hollow-cathode discharge
containing barium that were taken with the aid of a Fourier-transform
spectrometer (FTS). We have determined the branching fractions for ten
upper levels of the neutral barium atom. In the case of the resonance
level 6s6p <SUP>1</SUP>P° <SUB>1</SUB>, we had to augment our FTS
measures with literature data that had recently been obtained by use of
different laser-excitation techniques. Using four published lifetimes
and also through combining our emission measurements with relative
absorption data from the literature, we could convert the branching
fractions of eight upper levels into transition probabilities. The
resulting A values (with accuracies ranging from 1% to 60%) give support
to the correction of earlier literature data, recommended by Jahreiss
and Huber [Phys. Rev. A 31, 692 (1985)].
---------------------------------------------------------
Title: Das Projekt SOHO (Solar and Heliospheric-Observatory) im
Rahmen des solarterrestrischen Großvorhabens der ESA
Authors: Huber, M. C. E.
1987MitAG..68...71H Altcode:
No abstract at ADS
---------------------------------------------------------
Title: 10th European Regional Astronomy Meeting of the IAU, held in
Praha, Czechoslovakia, 24 - 29 August 1987. Programme of the Meeting
and Directory to the Proceedings.
Authors: Perek, L.; Zavřel, J.; Říman, J.; Bumba, V.; Lindblad,
P. O.; Huber, M. C. E.
1987PAICz..65.....P Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Staff Movements
Authors: Huber, M. C. E.
1986Msngr..45...36H Altcode:
Los astronomos de ESO dedican una considerable parte de su tiempo
a la preparacion de solicitudes para tiempo de observacion en La
Silla. Sin embargo, debido a la gran demanda par los telescopios,
se debe hacer una seleccion, aveces drastica, de los programas de
observacion presentados. EI Comite de Programas de Observacion (OPC)
tiene como tarea evaluar el merito cientifico de las solicitudes
presentadas. Basada en las recomendaciones dei OPC, ESO prepara
una Lista de Tiempos de Observacion en la cual distribuye el tiempo
disponible en los telescopios a los programas mejor evaluados.
---------------------------------------------------------
Title: The work of the ESO Observing Programmes Committee.
Authors: Huber, M. C. E.; Breysacher, J.
1986Msngr..45....2H Altcode:
ESO astronomers devote considerable time to preparing, and put obvious
care into writing Applications for Observing Time at La Silla. Many
take justifiable pride in the presentation of their ideas. Yet, given
the heavy oversubscription of telescope time, inevitably a selection
of the proposed observing programmes must be made. And often this
selection is drastic: in each Observing Period, the applied-for number
of observing nights for the various telescopes exceeds the number of
available nights by factors of two, at telescopes of intermediate size,
to four, at the 2.2-m and 3.6-m telescopes!
---------------------------------------------------------
Title: The measurement of oscillator strengths
Authors: Huber, M. C. E.; Sandeman, R. J.
1986RPPh...49..397H Altcode:
Linear and nonlinear techniques for measuring oscillator strengths in
atomic spectroscopy are examined in a detailed review. The linear
and nonlinear susceptibilities and the radiative constants are
defined; the fundamental principles of the methods are outlined;
and specific dispersion-based, absorption/emission-based, Ladenburg,
nonlinear-interaction, and laser methods are characterized.
---------------------------------------------------------
Title: An imaging extreme ultraviolet spectrometer for astrophysical
investigations in space.
Authors: Huber, M. C. E.; Timothy, J. G.; Morgan, J. S.; Lemaître,
G.; Tondello, G.; Puiatti, M. E.; Scarin, P.
1986SPIE..627..363H Altcode:
A high-efficiency, extreme ultraviolet (EUV) imaging spectrometer
has been constructed and tested. The spectrometer employs a concave
toroidal grating illuminated at normal incidence in a Rowland circle
mounting and has only one reflecting surface. The toroidal grating
has been fabricated by a new technique employing an elastically
deformable submaster grating which is replicated in a spherical
form and then mechanically distorted to produce the desired aspect
ratio of the toroidal surface for stigmatic imaging over the selected
wavelength range. The fixed toroidal grating used in the spectrometer
is then replicated from this surface. Photographic tests and initial
photoelectric tests with a two-dimensional, pulse-counting detector
system have verified the image quality of the toroidal grating
at wavelengths near 600 A. The basic designs of two instruments
employing the spectrometer for astrophysical investigations in space
are described, namely, a high-resolution EUV spectroheliometer for
studies of the solar chromosphere, transition region, and corona;
and an EUV spectroscopic telescope for studies of nonsolar objects.
---------------------------------------------------------
Title: Transition probabilities in Cr I.
Authors: Tozzi, G. P.; Brunner, A. J.; Huber, M. C. E.
1985MNRAS.217..423T Altcode:
Branching fractions have been measured for 60 Cr I lines that originate
from 14 different upper levels, with energies ranging from 3.3 to
6.9 eV. The measurements, obtained on the solar Fourier-Transform
Spectrometer on Kitt Peak, cover a wavelength range extending from
about 290 to 900 nm. The branching fractions, together with level
lifetimes determined by use of laser excitation by Kwiatkowski
et al. (1981), yield transition probabilities with an accuracy of
about 7 percent. A comparison with the precision data determined in
an absorption experiment at Oxford by Blackwell, Menon and Petford
(1982, 1983, 1984) shows no systematic trends, and thus provides for
the first time an independent upper limit on the claimed uncertainty
of the Oxford data.
---------------------------------------------------------
Title: Science with SOHO.
Authors: Huber, M. C. E.; Malinovsky-Arduini, M.
1984ESASP.220..177H Altcode: 1984ESPM....4..177H
The scientific goals of the Solar and Heliospheric Observatory (SOHO)
comprise the basic and interconnected questions regarding the interior
structure of the Sun, the heating of the corona and its expansion as
solar wind. The observations needed to pursue these questions will
be taken from a halo orbit around Lagrange point L<SUB>1</SUB> on the
Earth-Sun line, which offers uninterrupted observations of the Sun and
- lying outside the magnetosphere - of its solar-wind streams. In this
paper the authors outline some patent solar and heliospheric problems,
define the resulting observing needs and present the SOHO model payload
(helioseismology, optical plasma diagnostics of the corona at extreme
ultraviolet (XUV) and visible wavelengths, in-situ particle and field
measurements) in the light of these requirements.
---------------------------------------------------------
Title: Branching Ratios of the 2s<SUP>2</SUP>3p
<SUP>2</SUP>P<SUP>0</SUP> Term of Singly-Ionized Carbon
Authors: Huber, M. C. E.; Sandeman, R. J.; Tozzi, G. P.
1984PhST....8...95H Altcode: 1984PhyS....8...95H
The branching ratios of the 2s<SUP>2</SUP>3p
<SUP>2</SUP>P<SUP>0</SUP><SUB>1/2,3/2</SUB> levels of C<SUP>+</SUP>
have been measured by use of a Fourier-transform spectrometer and a
vacuum ultraviolet spectrometer. Experimental determination of these
branching ratios is of interest, because two-electron transitions
are involved, and calculations therefore may have larger than usual
uncertainties. The strong multiplets occurring at 658, 284, and 176 nm
can be used for determining the interstellar extinction between the
red and vacuum ultraviolet spectral regions. The reported branching
ratios may also be of use for calibrating the spectral radiometric
efficiency of laboratory spectrometers with beam-foil or plasma sources.
---------------------------------------------------------
Title: Recommendations on post focus instrumentation for LEST.
Authors: Wöhl, H.; Huber, M. C. E.; Mein, P.; Smaldone, L.
1984LFTR....5.....W Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Branching ratios in the vacuum ultraviolet spectrum of
neutral carbon
Authors: Tozzi, G. P.; Huber, M. C. E.; Pauls, U.
1983A&A...126..320T Altcode:
The relative strengths of allowed and intercombination transitions
out of the 3s<SUP>3</SUP>P<SUP>0</SUP>, 2p<SUP>3</SUP>
<SUP>3</SUP>P<SUP>0</SUP> and <SUP>3</SUP>D<SUP>0</SUP>,
3d<SUP>3</SUP>P<SUP>0</SUP> and <SUP>3</SUP>D<SUP>0</SUP> as well as
4s<SUP>3</SUP>P<SUP>0</SUP> terms belonging to neutral carbon have
been measured. Some of the allowed multiplets exhibit deviations from
LS-coupling. Implications of the measurements regarding the spectra
of the interstellar medium, of comets and chromospheres are mentioned.
---------------------------------------------------------
Title: Branching-Ratio Measurements of the Fine Structure of C I.
Authors: Huber, M. C. E.; Tozzi, G. P.; Yoshino, K.
1982uxsa.coll...10H Altcode: 1982IAUCo..73...10H
No abstract at ADS
---------------------------------------------------------
Title: The ESA project for a Grazing Incidence Solar Telescope
(GRIST).
Authors: Huber, M. C. E.
1981SoPh...74..539H Altcode:
The Grazing Incidence Solar Telescope (GRIST) as it is being studied
by the European Space Agency (ESA) is described: A soft X-ray and
extreme-ultraviolet (XUV) facility for solar observations with 1
arc sec spatial resolution in a wavelength range extending from 9
to beyond 100 nm. The telescope, a 35° sector of a Wolter, type-II,
configuration, will have a focal length of 4 m and a collection area
of 280 cm<SUP>2</SUP>.
---------------------------------------------------------
Title: Solar physics from space. Proceedings of a conference held
at ETH Zurich, November 11 - 14, 1980.
Authors: Huber, M. C. E.
1981SSRv...29..295H Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Solar physics from space; Proceedings of the Conference,
Eidgenoessische Technische Hochschule Zuerich, Zurich, Switzerland,
November 11-14, 1980
Authors: Huber, M. C. E.
1981SSRv...29.....H Altcode:
Topics discussed include the Grazing Incidence Solar (GRIST) and Solar
Optical (SOT) Telescopes, atomic data and magnetic field measurements,
and solar and related stellar physics. Particular attention is given
to the instrumentation and joint accomodation of GRIST and SOT, the
acoustic and magnetoacoustic heating of the outer atmospheres of stars,
magnetic fine structures and granular velocities, and the Hanle effect
applied to magnetic field diagnostics. Consideration is also given to
high-resolution ultraviolet solar observations from sounding rockets,
high resolution grazing incidence telescopes for the EUV regime,
and X-ray and extended UV spectrometer designs based on off-plane
grating mountings.
---------------------------------------------------------
Title: Activity and outer atmospheres of the sun and stars. Eleventh
Advanced Course of the Swiss Society of Astronomy and Astrophysics,
held in Saas-Fee, Switzerland, March 30 - April 4, 1981.
Authors: Benz, A. O.; Chmielewski, Y.; Huber, M. C. E.; Nussbaumer, H.
1981aoas.book.....B Altcode:
No abstract at ADS
---------------------------------------------------------
Title: A solar abundance of nickel independent of line broadening
parameters
Authors: Biemont, E.; Grevesse, N.; Huber, M. C. E.; Sandeman, R. J.
1980A&A....87..242B Altcode:
The solar abundance of nickel is determined on the basis of two
recent sets of accurate f values independent of line broadening
parameters. Solar equivalent widths of 12 very weak neutral nickel lines
between 3946.200 and 7062.978 A for which accurate oscillator strengths
were available were measured on spectra of the center of the solar disk,
and solar profiles were computed by the direct integration of profiles
using two different empirical solar models in the LTE hypothesis. A
photospheric nickel abundance of 6.22 plus or minus 0.13 is obtained,
in reasonable agreement with coronal values and in excellent agreement
with the abundance of Ni in chondritic meteorites.
---------------------------------------------------------
Title: Oscillator strengths of ultraviolet NI I lines from hook-method
and absorption measurements in a furnace
Authors: Huber, M. C. E.; Sandeman, R. J.
1980A&A....86...95H Altcode:
Measurements of the oscillator strengths of the ultraviolet lines of
neutral nickel obtained by the use of the combined hook and absorption
technique are reported. A total of 221 transitions in the range
1964-4094 A was measured for nickel atoms from a high-temperature
graphite furnace (2000-2500 K) using a continuum background source, a
Mach-Zehnder interferometer and a 3-m Czerny-Turner spectrograph. Hook
and absorption measurements are presented, and radiative lifetimes
are derived from log gf values. Comparison of the present values with
previous results indicates only those of Bell et al. (1966) and Lennard
et al. (1975) to consistently agree with the data presented, although
the reliability laser-excitation technique of lifetime measurement is
supported over that of Hanle methods.
---------------------------------------------------------
Title: A solar abundance of nickel independent of line broadening
parameters.
Authors: Biémont, E.; Grevesse, N.; Huber, M. C. E.; Sandeman, R. J.
1980A&A....84..242B Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Contribution to Solar Physics from extreme-ultraviolet
observations
Authors: Huber, M. C. E.; Withbroe, G. L.
1980fsoo.conf..146H Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Transition probabilities and their accuracy.
Authors: Huber, M. C. E.; Sandeman, R. J.
1980PhyS...22..373H Altcode:
The classical methods for measuring transition probabilities, viz. the
determination of lifetimes and branching ratios, and the absorption,
hook, and emission techniques are briefly reviewed. The main advantages
and difficulties of each method, as well as the accuracies reached,
are described. Improved evaluation methods for hook spectrograms are
summarized and the advances made with combinations of classical methods
for determining and assessing oscillator strengths are described. The
hitherto rarely exploited potential of magneto-rotation measurements for
deriving accurate oscillator strengths and the promise of optogalvanic
spectroscopy are mentioned. Applications of non-linear optical methods
for f-value determinations are also discussed.
---------------------------------------------------------
Title: Stigmatic performance of an EUV spectrograph with a single
toroidal grating
Authors: Huber, M. C. E.; Tondello, G.
1979ApOpt..18.3948H Altcode:
The paper describes an EUV spectrograph which uses a single toroidal
grating to generate a near-stigmatic spectrum over an extended
wavelength range. It can observe the solar corona dynamics in the 520
to 630 A wavelength range using a 3600-line/mm grating that generates
images with a blur of less than 20 microns over an area 2.6 mm high
by 80 mm wide; over an area 6 mm by 80 mm the blur does not exceed 40
microns. If the spectrograph is equipped with a 20-micron wide entrance
slit which is placed in the focal plane of 4 m focal length telescope,
spatial resolution elements of 1 by 1 (sec of arc) sq and 1 by 2
(sec of arc) sq result over 2 min of arc and 5 min of arc respective
slit heights.
---------------------------------------------------------
Title: IUE observations of absorption by hot gas in the nebula NGC6888
Authors: Huber, M. C. E.; Nussbaumer, H.; Smith, L. J.; Willis, A. J.;
Wilson, R.
1979Natur.278..697H Altcode:
New UV observations of Wolf-Rayet stars obtained with the IUE satellite
show narrow absorption components in the highly ionized species of
Si IV and C IV. In the case of the WN6 star HD 192163 each resonance
transition in the above ions exhibits two components, one undisplaced
in wavelength and one blueshifted. The latter components are shown to
arise in the nebula NGC 6888 surrounding HD 192163, and these are the
first observations of absorption lines arising in a nebula associated
with an early-type star. The strengths of the 'interstellar' Si IV
and C IV lines in four WR stars and two other early-type stars are
compared. There seems to be no correlation in the strengths of these
lines with either stellar distance or color excess, suggesting that
they arise not in the general interstellar medium but in material more
intimately linked with the stars themselves.
---------------------------------------------------------
Title: IUE observations of interstellar SI IV and C IV lines and
absorption by hot gas in the ring nebula NGC 6888
Authors: Smith, L. J.; Willis, A. J.; Wilson, R.; Huber, M. C. E.;
Nussbaumer, H.
1979IUE1.symp...18S Altcode:
Recent IUE observations of Wolf-Rayet stars show narrow absorption
lines in the highly ionised species of Si IV and C IV. In the case of
HD 192163 each resonance transition in the above ions exhibits two
components, one undisplaced in wavelength and one blue-shifted. It
is shown that the latter components arise in the nebula NGC 6888
surrounding HD 192163, and these data represent the first observations
of absorption lines arising in a nebula associated with an early-type
star. The strengths of the 'interstellar' Si IV and C IV lines in
ten WR stars and two other early-type stars are compared. Of the WR
sample, six stars exhibit strong Si IV and C IV lines (W-wavelength
is about 0.3 - 0.5 A) whilst the other four show much weaker lines
(W-wavelength is about 0.1A). There appears to be no correlation in
the strengths of these lines with either stellar distance or colour
excess. The weaker absorptions may arise in the H II region of the
stars in question; the observed strengths being consistent with those
expected for stars with T(eff) about 30000 K. Five of the remaining
six stars which exhibit strong C IV and Si IV absorption lie in the
line of sight to supernovae remnants (Cygnus and Carina) and it is
probable that, in addition to the stars's own H II region components,
the bulk of the strong absorptions seen in these stars originate in
hot gas associated with these active regions.
---------------------------------------------------------
Title: Contributions to solar physics from extreme-ultraviolet
observations.
Authors: Huber, M. C. E.; Withbroe, G. L.
1979MmArc.106..146H Altcode:
No abstract at ADS
---------------------------------------------------------
Title: On the chromium abundance in the solar photosphere.
Authors: Biemont, E.; Grevesse, N.; Huber, M. C. E.
1978A&A....67...87B Altcode:
Summary. The solar abundance of chromium is inferred from high-quality
photospheric spectra with the aid of several recent sets of experimental
and theoretical oscillator strengths for Cr 1. The mean abundance,
Acr = log (Ncr/N ) + 12 = 5.64, obtained with an LTEanalysis, agrees
with the meteoritic value. The uncertainty of Acr stemming from the
oscillator strengths is +0.03 dex only; an additional uncertainty of
the order of +0.1 dex may, however, have to be assigned to the solar
model calculations that yield the abundance. Key words: chromium
abundance - gf-values.
---------------------------------------------------------
Title: Contribution to Solar Physics from extreme-ultraviolet
observations
Authors: Huber, M. C. E.; Withbroe, G. L.
1978fsoo.conf..146H Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Spectra of high-resolution heliograms in the
extreme-ultraviolet by use of toroidal gratings.
Authors: Tondello, G.; Huber, M. C. E.
1978JOSA...68R1431T Altcode: 1978OSAJ...68R1431T
No abstract at ADS
---------------------------------------------------------
Title: Optical design of a stigmatic spectroheliometer for photometric
studies of dynamic phenomena at extreme-ultraviolet wavelengths.
Authors: Huber, M. C. E.; Timothy, J. G.
1977SSI.....3..389H Altcode:
The design of a stigmatic spectroheliometer for photometric studies
of dynamic phenomena in the solar atmosphere at extreme ultraviolet
(EUV) wavelengths is described. The normal-incidence spectrometer
requires only one reflective surface, and is equipped with a series
of exit slits and associated one-dimensional detector arrays that are
mounted at the secondary (vertical) foci of the concave diffraction
grating. It is shown that such a spectrometer mounted at the focus of
an off-axis paraboloid telescope mirror of the size employed in the EUV
spectroheliometer flown on Skylab could record monochromatic images of
a 2 x 2 (arcmin) sq field-of-view with a spatial resolution element
of 1 x 1 (arcsec) sq in a time of 4 s, 24 s, or 4 min, depending on
whether the region studied is flaring, active, or quiet. The resulting
spectroheliograms would have an average photometric precision of 10%
and a spectral purity of 0.1 A.
---------------------------------------------------------
Title: Oscillator Strengths of Cr I Lines Lying between 200 and 541
nm from Hook-Method and Absorption Measurements in a Furnace
Authors: Huber, M. C. E.; Sandeman, R. J.
1977RSPSA.357..355H Altcode:
Oscillator strengths of 148 transitions in the neutral chromium
atom with wavelengths between 200 and 541 nm were determined in a
high-temperature furnace by use of the hook and absorption methods
for strong and weak lines, respectively. 114 of these gf-values
are reported for the first time. Hook spectra taken at wavelengths
near 430 nm assured accurate knowledge of the product of f-value and
column density for prominent transitions with lower levels lying at
0 and ≈ 1 eV. The absolute scale is based on the best available
oscillator strengths for the 427 nm resonance triplet. The relative
scale matches measurements of the relative intensities of emission
lines that correspond to transitions from a common upper level
(z <SUP>5</SUP>P<SUB>2</SUB><SUP>0</SUP>) to the ground level (a
<SUP>7</SUP>S<SUB>3</SUB>) as well as to excited terms (a <SUP>5</SUP>S,
a <SUP>5</SUP>D). A slight adjustment (well within the calibration
uncertainties) made our oscillator-strength scale agree with gf-values
obtained by Cocke, Stark & Evans from beam-foil and branching-ratio
measurements. Uncertainty estimates, given for each oscillator strength,
are substantiated by the agreement (within error limits) of those
f-values that could be measured by both, absorption and hook method.
---------------------------------------------------------
Title: Extreme UV spectroheliometer on the Apollo Telescope Mount.
Authors: Reeves, E. M.; Huber, M. C. E.; Timothy, J. G.
1977ApOpt..16..837R Altcode:
The extreme UV spectroheliometer flown on ATM observed within the
280-1340 A spectral range at seven wavelengths simultaneously, with
a spatial resolution element 5 x 5 sq arcsec field of view in 5.5
min. The instrument could also obtain spectral scans over the same
wavelength range with a spectral resolution of 1.6 A in 3.8 min. The
instrument is described in detail with attention given to the telescope,
the spectrometer, and the detection system.
---------------------------------------------------------
Title: Photometric calibration of the EUV spectroheliometer on ATM.
Authors: Reeves, E. M.; Timothy, J. G.; Huber, M. C. E.; Withbroe,
G. L.
1977ApOpt..16..849R Altcode:
This paper describes the derivation of the preflight photometric
calibration of the UV spectrometer on Skylab. The calibration of the
orbiting instrument through cross-comparison with two rocket instruments
is discussed in assessing the observed changes in response to quiet
solar regions during the mission. Formulas are presented for the
determination of the instrument sensitivity, and an uncertainty of plus
or minus 35% is assigned over most of the 296-1340-A wavelength range.
---------------------------------------------------------
Title: f-value measurements for 3d-elements.
Authors: Huber, M. C. E.
1977PhyS...16...16H Altcode:
We give a survey of data on transition probabilities of allowed lines
that belong to the spectra of neutral and singly-ionized iron-group
elements. The classical methods used to determine oscillator
strengths of weak lines (usually on a relative scale) are reviewed
and some of the difficulties arising in investigating the spectra of
3d-elements are pointed out. The quality of experimental lifetimes
and f-values of strong lines, i.e., of data which are frequently
used to establish absolute scales, are discussed in the context of
the methods employed. The results on weak lines are then assessed,
element by element, and some applications are mentioned. It is
concluded that further, more precise measurements are needed, since
a given oscillator strength of a weak line is, in most cases, known
within a factor of 1.5 or 2 only. The importance of confirming existing
data is stressed. An urgent need is found to exist for better data on
singly-ionized 3d-elements.
---------------------------------------------------------
Title: Refractivities of H<SUB>2</SUB>, He, O<SUB>2</SUB>, CO,
and Kr for 168<=λ<=288 nm
Authors: Smith, Peter L.; Huber, Martin C. E.; Parkinson, W. H.
1976PhRvA..13.1422S Altcode:
Precision measurements of the refractivities of H<SUB>2</SUB>, He,
O<SUB>2</SUB>, CO, and Kr were made in the wavelength range 168-288
nm. By using a 1.2-m-long test cell and by keeping the test gas at
accurately determined conditions near atmospheric pressure and room
temperature, we were able to achieve accuracies (90% confidence limit)
for the absolute refractivities that ranged from +/-0.1% to +/-1.0%
depending upon the gas and wavelength range. For a given gas, the ratio
of refractivities at any two wavelengths has a smaller uncertainty. For
H<SUB>2</SUB>, CO, and O<SUB>2</SUB>, our results are for wavelengths
shorter than those of previous measurements and, for He and Kr, our
uncertainties are less than those of other measurements. For He our
refractivities agree with the theoretical ones, but in the case of
H<SUB>2</SUB> our results are about 1% larger than the theoretical
values. At the upper end of the wavelength range studied, our data
are in agreement with previous measurements on H<SUB>2</SUB>, CO, and
Kr. For O<SUB>2</SUB> our results indicate that the hitherto available
data are too large by amounts ranging from 0.8% to 10%.
---------------------------------------------------------
Title: Extreme-ultraviolet transients observed at the solar pole.
Authors: Withbroe, G. L.; Jaffe, D. T.; Foukal, P. V.; Huber, M. C. E.;
Noyes, R. W.; Reeves, E. M.; Schmahl, E. J.; Timothy, J. G.; Vernazza,
J. E.
1976ApJ...203..528W Altcode:
Extreme-ultraviolet (EUV) observations of two polar transient features
('macrospicules') are described. These features appear to be caused
by jets of chromospheric material that shoot upward to a height of
35,000 km above the limb and then fall back into the chromosphere,
reaching terminal velocities of about 140 km/s. On the basis of a
model developed from the EUV measurements, it is found that the energy
required to produce each event is about 3 by 10 to the 26th power ergs,
about two orders of magnitude more than that required to produce an
ordinary spicule. This indicates that macrospicules may be an important
factor in the energy balance of the chromosphere and corona.
---------------------------------------------------------
Title: Initial results from the EUV spectroheliometer on ATM
Authors: Reeves, E. M.; Timothy, J. G.; Foukal, P. V.; Huber, M. C. E.;
Noyes, R. W.; Vernazza, J. E.; Withbroe, G. L.; Schmahl, E. J.
1976skls.conf...73R Altcode:
The Harvard College Observatory photoelectric spectroheliometer on
the Apollo Telescope Mount operated correctly in orbit from May 29,
1973 to February 7, 1974. During this period, many thousands of
spatial and spectral scans at extreme ultraviolet wavelengths were
recorded during observations of a variety of solar features. The
construction and modes of operation of the instrument are outlined,
and the principal scientific results from a preliminary analysis of
the data are described.
---------------------------------------------------------
Title: Time variations in extreme-ultraviolet emission lines and
the problem of coronal heating.
Authors: Vernazza, J. E.; Foukal, P. V.; Huber, M. C. E.; Noyes,
R. W.; Reeves, E. M.; Schmahl, E. J.; Timothy, J. G.; Withbroe, G. L.
1975ApJ...199L.123V Altcode:
We have analyzed the time structure of the intensity of solar
chromospheric and coronal extreme-ultraviolet lines, obtained by
the Harvard College Observatory spectrometer aboard Skylab. We find
changes in the intensity of up to 50 percent in times as short as
1 minute, but not periodic oscillations. Some evidence is found for
the presence of shock waves in the chromosphere and the transition
region. It is suggested that the solar chromosphere and corona are
heated by nonperiodic waves.
---------------------------------------------------------
Title: EUV Observations of the Active Sun from the Harvard Experiment
on ATM
Authors: Noyes, R. W.; Foukal, P. V.; Huber, M. C. E.; Reeves, E. M.;
Schmahl, E. J.; Timothy, J. G.; Vernazza, J. E.; Withbroe, G. L.
1975IAUS...68....3N Altcode:
Some extreme UV observations of solar active regions made with a
scanning spectroheliometer are described. Spectroheliograms constructed
from digital data using a computer-driven cathode-ray tube display show
clearly how the appearance of an active region changes as a function
of temperature. Flare studies indicate that the impulsive rise in
EUV emission occurs essentially simultaneously at all levels from the
transition zone to the corona. Observations of sunspots reveal a very
intense emission in transition zone lines. A matrix of Mg x rasters
covering the entire sun reveals several hundred bright points having
dimensions of 30 arc seconds or less. Other observations include
coronal holes and prominences.
---------------------------------------------------------
Title: Atomic and molecular processes in astrophysics. Fifth Advanced
Course of the Swiss Society of Astronomy and Astrophysics.
Authors: Huber, M. C. E.; Nussbaumer, H.
1975ampa.book.....H Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Extreme-Ultraviolet Observations of Coronal Holes: Initial
Results from SKYLAB
Authors: Huber, M. C. E.; Foukal, P. V.; Noyes, R. W.; Reeves, E. M.;
Schmahl, E. J.; Timothy, J. G.; Vernazza, J. E.; Withbroe, G. L.
1974ApJ...194L.115H Altcode:
We compare the appearance and physical parameters of the solar
chromosphere, transition zone, and corona in areas of coronal holes
with that of quiet areas outside the hole. Measurements of the height
of emission of various ions in a coronal hole appearing at the polar
limb give a quantitative indication of the increased thickness of the
transition zone underlying coronal holes.
---------------------------------------------------------
Title: Extreme-Ultraviolet Observations of Sunspots with the Harvard
Spectrometer on the Apollo Telescope Mount
Authors: Foukal, P. V.; Noyes, R. W.; Reeves, E. M.; Schmahl, E. J.;
Timothy, J. G.; Vernazza, J. E.; Wilhbroe, G. L.; Huber, M. C. E.
1974ApJ...193L.143F Altcode:
EUV spectroheliograms show that the areas directly above sunspot
umbrae are the brightest features in an active region by an order of
magnitude in the chromospherecorona transition region (1 K < T <
108 K.) Rarios of density-sensitive lines in the transition region
show a significant decrease in gas density over the umbra relative
to surrounding plage. We deduce that the temperature gradient in the
transition region over the spot is decreased by an order of magnitude
or more, relative to the plage. S#ject headings: chromosphere, solar -
corona, solar - spectroheliograms - sunspots
---------------------------------------------------------
Title: Initial results from the EUV spectroheliometer on ATM.
Authors: Reeves, E. M.; Timothy, J. G.; Foukal, P. V.; Huber, M. C. E.;
Noyes, R. W.; Schmahl, E. J.; Vernazza, J. E.; Withbroe, G. L.
1974aiaa.conf.....R Altcode:
The Harvard College Observatory photoelectric spectroheliometer on
the Apollo Telescope Mount operated correctly in orbit from May 29,
1973 to Feb. 7, 1974. During this period many thousands of spatial and
spectral scans at extreme ultraviolet wavelengths were recorded during
observations of a variety of solar features. The construction and modes
of operation of the instrument are outlined and the principal scientific
results from a preliminary analysis of the data are described.
---------------------------------------------------------
Title: Extreme Ultraviolet Solar Spectra from Skylab-Apollo Telescope
Mount.
Authors: Dupree, A. K.; Foukal, P. V.; Huber, M. C. E.; Noyes, R. W.;
Reeves, E. M.; Schmahl, E. J.; Timothy, J. G.; Vernazza, J. E.;
Withbroe, G. L.
1974BAAS....6..349D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Hook-Method Measurements of gf-values for Ultraviolet Fe I
and Fe II Lines on a Shock Tube
Authors: Huber, Martin C. E.
1974ApJ...190..237H Altcode:
Transition probabilities for 14 lines of Fe ii and 12 lines of Fe I in
the wavelength region 25602737 A were measured by use of a shock tube
and the hook method. Absolute oscillator strengths for resonance lines
of Fei reported by Banfield and Huber were used to determine the number
density of neutral iron in the shock-heated gas. With the assumption of
thermal equilibrium, the density of singly ionized iron atoms in this
gas was then computed from the measured temperature and pressure with
the aid of the Saha equation. Our results on the 12 strongest of the
13 lines belonging to the first ultraviolet multiplet of Fe ii indicate
that the multiplet f-value is larger by a factor of 2 than that derived
from lifetime measurements by Assousa and Smith. Subject headings:
spectra, laboratory - spectra, ultraviolet - transition probabilities
---------------------------------------------------------
Title: Extreme Ultraviolet Solar Observations from the Harvard
ATM Experiment
Authors: Withbroe, G. L.; Foukal, P. K.; Huber, M. C. E.; Noyes,
R. W.; Reeves, E. M.; Schmahl, E. J.; Timothy, J. G.; Vernazza, J. E.
1974BAAS....6V.297W Altcode:
No abstract at ADS
---------------------------------------------------------
Title: ATM Observations of the Time Dependent Intensity Fluctuations
in the Extreme Ultraviolet
Authors: Vernazza, J. E.; Foukal, P. K.; Huber, M. C. E.; Noyes,
R. W.; Reeves, E. M.; Schmahl, E. J.; Timothy, J. G.; Withbroe, G. L.
1974BAAS....6R.296V Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Solar Prominences in the Extreme Ultraviolet as Observed from
the Apollo Telescope Mount
Authors: Schmahl, E. J.; Foukal, P. V.; Huber, M. C. E.; Noyes, R. W.;
Reeves, E. M.; Timothy, J. G.; Vernazza, J. E.; Withbroe, G. L.
1974SoPh...39..337S Altcode:
Observations of quiescent solar prominences with the Harvard College
Observatory spectrometer abroad Skylab show that prominence material is
optically thick in the Lyman alpha line and the Lyman continuum. The
color temperature of the Lyman continuum has a mean of 6600 K and
an upward gradient toward the top of the prominence. The departure
coefficient of the ground state of hydrogen is found to be of the
order of unity as expected from theory.
---------------------------------------------------------
Title: Observations of the Chromospheric Network: Initial Results
from the Apollo Telescope Mount
Authors: Reeves, E. M.; Foukal, P. V.; Huber, M. C. E.; Noyes, R. W.;
Schmahl, E. J.; Timothy, J. G.; Vernazza, J. E.; Withbroe, G. L.
1974ApJ...188L..27R Altcode:
A preliminary analysis of early data taken by the HCO spectrometer on
Skylab shows that the solar chromospheric network can be clearly seen
with varying contrast in the extreme-ultraviolet emission characteristic
of temperatures between 10 v K (the Lyman continuum) and 3 X 10 K (0
vi). In the emission of Mg x, a coronal line formed at about 1.5 X 108
K, the network is generally unrecognizable. This is interpreted as being
due to a spreading of the magnetic field lines of the network boundary
in the height interval corresponding to the temperature difference
between 3 X 10 and 1.5 X 108 K. We note that in certain anomalous cases,
bright points of the network are seen to extend with high contrast and
essentially unchanged in their cross-section through the full range of
temperatures characteristic of the chromosphere, transition region,
and low corona. Subject headings: granules and supergranules, solar-
spectra, ultraviolet
---------------------------------------------------------
Title: Solar EUV Photoelectric Observations from SKYLAB
Authors: Reeves, E. M.; Foukal, P. V.; Huber, M. C. E.; Noyes, R. W.;
Schmahl, E. J.; Timothy, J. G.; Vernazza, J. E.; Withbroe, G. L.
1974IAUS...57..497R Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The photoelectric spectroheliometer on ATM
Authors: Reeves, E. M.; Timothy, J. G.; Huber, M. C. E.
1974SPIE...44..159R Altcode:
The Harvard College Observatory instrument on the Skylab Apollo
Telescope Mount is a photoelectric spectroheliometer designed to
obtain up to seven simultaneous spectroheliograms in the range between
280 and 1340 A with a spatial resolution of 5 arc sec, as well as
spectral scans with a resolution of 1.6 A over the same range of
wavelengths. The optical schematic of the instrument is illustrated
and discussed. Because of its large size, the instrument has a
sensitivity far greater than that of any other EUV spectroheliometer
flown to date. The instrument has operated correctly in orbit since May
1973. Valuable data have been obtained during this period on a variety
of solar phenomena, on the comet Kohoutek, and on the atmospheres of
the earth and Mercury. The instrument was successfully recalibrated
in orbit by comparing the response with that of recently calibrated
spectroheliometers flown on sounding rockets.
---------------------------------------------------------
Title: The photoelectric spectroheliometer on ATM.
Authors: Reeves, E. M.; Timothy, J. G.; Huber, M. C. E.
1974inas.conf..159R Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Photometric Calibration of an Extreme-Ultraviolet
Spectroheliometer for the Skylab Mission
Authors: Huber, M. C. E.; Reeves, E. M.; Timothy, J. G.
1974spop.conf...33H Altcode:
No abstract at ADS
---------------------------------------------------------
Title: A Photospheric Solar Iron Abundance Independent of Line-Shape
Parameters
Authors: Huber, Martin C. E.; Tubbs, Eldred F.
1973ApJ...186.1053H Altcode:
The solar iron abundance has been determined from the 5127.68 A
resonance line of Fe i. This line has an equivalent width small enough
to make the derived abundance nearly independent of assumptions on
line-shape parameters. Blending of the line by molecular lines has
been allowed for, and the sensitivity of the resulting abundance
to the choice of a particular model atmosphere (including non-LTE)
was assessed. The abundance, log (NF6/NH) + 12 = 7.64( + 0.18/ -
0.20), is in good agreement with that derived from three stronger
resonance lines, provided that a microturbulent parameter of 0.5 km s
' is assumed and the damping is estimated to have 20 to 30 times the
classical value. Subject headings: abundances, solar - line profiles -
spectra, solar
---------------------------------------------------------
Title: Oscillator Strengths of Ultraviolet Fe I Lines from Hook-Method
Measurements on a Furnace
Authors: Banfield, Francis P.; Huber, Martin C. E.
1973ApJ...186..335B Altcode:
The hook method, which makes use of anomalous dispersion, was
employed to measure 107 absolute oscillator strengths of Fe I on a
high-temperature furnace. The absolute scale was established before
and after each run by recording the anomalous dispersion near a
strong resonance line with accurately known f-value. The results cover
three lines with wavelengths 1934-1941 A, and 104 lines lying between
2084 and 3194 A-mostly transitions originating from the a 5D ground
state. The average error of the f-values is I 20 percent, and the
largest and smallest errors given are I 10 and I 60 percent. We find
disagreements, exceeding an order of magnitude, with previous values
in the literature. Subject headings: spectra, laboratory - spectra,
ultraviolet - transition probabilities
---------------------------------------------------------
Title: A Study of the Active Region McMath 12417 with the Harvard
ATM EUV Spectrometer.
Authors: Foukal, P. V.; Huber, M. C. E.; Noyes, R. W.; Reeves, E. M.;
Schmahl, E. J.; Timothy, J. G.; Vernazza, J. E.; Withbroe, G. L.
1973BAAS....5..432F Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Preliminary Solar Extreme Ultraviolet Observations from the
ATM with the Harvard Instrument.
Authors: Reeves, E. M.; Foukal, P. K.; Huber, M. C. E.; Noyes, R. W.;
Schmahl, E. J.; Timothy, J. G.; Vernazza, J. E.; Withbroe, G. L.
1973BAAS....5..419R Altcode:
No abstract at ADS
---------------------------------------------------------
Title: ATM Observations of Solar Flares in the Extreme Ultraviolet.
Authors: Noyes, R. W.; Foukal, P. V.; Huber, M. C. E.; Reeves, E. M.;
Schmahl, E. J.; Timothy, J. G.; Vernazza, J. E.; Withbroe, G. L.
1973BAAS....5..433N Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Solar Prominences-in the EUV as Observed from ATM.
Authors: Schmahl, E. J.; Foukal, P. V.; Huber, M. C. E.; Noyes, R. W.;
Reeves, E. M.; Timothy, J. G.; Vernazza, J. E.; Withbroe, G. L.
1973BAAS....5..432S Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Observations of a Coronal Hole Boundary in the Extreme
Ultraviolet.
Authors: Huber, M. C. E.; Foukal, P. V.; Noyes, R. W.; Reeves, E. M.;
Schmahl, E. J.; Timothy, J. G.; Vernazza, J. E.; Withbroe, G. L.
1973BAAS....5..446H Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The Harvard Experiment on OSO-6: Instrumentation, Calibration,
Operation, and Description of Observations
Authors: Huber, Martin C. E.; Dupree, A. K.; Goldberg, Leo; Noyes,
R. W.; Parkinson, W. H.; Reeves, E. M.; Withbroe, George L.
1973ApJ...183..291H Altcode:
The Harvard experiment carried by OS 0-6 was an extreme-ultraviolet
(EUV) spectrometerspectroheliometer with wavelength range 285-1385 A,
spatial and spectral bandwidth 35 x 35 (arc sec)2 and 3 A, respectively;
the instrumeflt acquired data that have been deposited with the National
Space Science Data Center and World Data Center A at the Goddard Space
Flight Center in Greenbelt, Maryland, and are now available in their
entirety to the scientific community. This paper describes aspects
of the experiment that are relevant to potential users of the data:
instrument configuration and parameters, laboratory and inflight
calibrations, as well as operational capabilities and procedures. We
also report the observations obtained and, where relevant, list
the nature, number, and dates of observations. Subject headings:
atmospheres, solar - instruments - solar activity - spectra, solar -
spectra, ultraviolet
---------------------------------------------------------
Title: Extreme-Ultraviolet Emission from Solar Prominences
Authors: Noyes, R. W.; Dupree, A. K.; Huber, M. C. E.; Parkinson,
W. H.; Reeves, E. M.; Withbroe, G. L.
1972ApJ...178..515N Altcode:
Spectra and spectroheliograms of prominences have been obtained at
wavelengths 300 A < A < 1400 A from instruments aboard the OSO 4
and OSO 6 spacecraft. Quiescent prominences appear in emission above
the limb for all strong lines formed at temperatures below 3 x 10 K,
but not at higher temperatures. The gas pressure in the 10 K transition
zone around prominences is approximately equal to that in the cooler
(6300 K) central regions. The temperature and the hydrogen ground-state
departure coefficient in the central regions are determined from
the Lymancontinuum spectrum. Prominences on the disk (filaments) are
visible in absorption in many lines, especially those at wavelengths
below the hydrogen Lyman limit at 912 A. The fractional absorption,
averaged over the spectrometer aperture, decreases regularly with
increasing temperature of line formation. The hydrogen La and Lfl lines
show only slight absorption relative to chromospheric lines lying on
top of the Lyman continuum.
---------------------------------------------------------
Title: Oscillator Strengths of Weak Fe I Resonance Lines Measured
by Combined Hook and Absorption Techniques
Authors: Huber, Martin C. E.; Tubbs, Eldred F.
1972ApJ...177..847H Altcode:
Oscillator strengths of nine weak Fe I resonance lines (Multiplet 1,
AA5 110-5255) determined from nearly simultaneous hook and photoelectric
absorption measurements are presented. Comparison of these results
with the commonly used oscillator strengths of Corliss and Tech
supports the hypothesis of Bell and Upson that the data reflect
an intensity-dependent error. The size of the intensity correction
determined from our results is somewhat larger than that predicted by
Bell and Upson.
---------------------------------------------------------
Title: The Solar Iron Abundance Revisited: A Determination from the
Weak Fe I Line λ5127.7
Authors: Huber, M. C. E.; Tubbs, E. F.
1972BAAS....4Q.385H Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Solar Flares in the Extreme Ultraviolet. I. The Observations
Authors: Wood, A. T., Jr.; Noyes, R. W.; Dupree, A. K.; Huber,
M. C. E.; Parkinson, W. H.; Reeves, E. M.; Withbroe, G. L.
1972SoPh...24..169W Altcode:
Solar-flare observations in the extreme ultraviolet (300-1350 Å) are
reported. Some 269 flares observed by the Harvard College Observatory
(HCO) experiment on OSO 4 and 211 flares observed by the HCO experiment
on OSO 6 have been analyzed. The flares were observed in spectral
lines and continua emitted by many ionic species over a temperature
range from 10<SUP>4</SUP> to 3.5 × 10<SUP>6</SUP> K. The EUV data
have been correlated with X-ray, Hα, and radio observations, and a
significant number of EUV bursts not associated with reported Hα,
X-ray, or radio bursts have been iden tified and investigated. The
results indicate that these latter EUV events are less energetic by
about a factor of 2 than EUV bursts associated with — F subflares.
---------------------------------------------------------
Title: F i Oscillator Strengths Determined from Anomalous Dispersion
of Shock-Heated Gases.
Authors: Huber, Martin C. E.; Parkinson, W. H.
1972ApJ...172..229H Altcode:
Fe I oscillator strengths measured by the hook method on shock-heated
gases are reported. Within the given errors these values agree
with oscillator strengths obtained by other methods, including
wallstabilized arc and shock-tube emission, the beam-foil technique,
and delayed-coincidence measurements, except that the data reported
here tend to be somewhat higher. If one assumes no change in atmospheric
models, our f-value scale would suggest a solar abundance at the lower
limit of the recently published values, namely, log (Ar /An) + 12 =
7.4. This study demonstrates the effectiveness of the hook method
for quantitative spectroscopy on shock-heated gases and points up its
usefulness for gas diagnostics on optically thick lines.
---------------------------------------------------------
Title: Coronal Electron Density Maps for 7 March, 1970, Derived from
Mgx λ625 Spectroheliograms (Papers presented at the Proceedings
of the International Symposium on the 1970 Solar Eclipse, held in
Seattle, U. S. A. , 18-21 June, 1971.)
Authors: Withbroe, G. L.; Dupree, A. K.; Goldberg, L.; Huber,
M. C. E. .; Noyes, R. W.; Parkinson, W. H.; Reeves, E. M.
1971SoPh...21..272W Altcode:
We have analyzed daily Mgx λ 625 spectroheliograms acquired by the
Harvard College Observatory experiment on OSO-6 for a 28-day period
centered on 7 March, 1970, the date of a well-observed total solar
eclipse. These data are used to construct maps of the variation across
the solar disk of the electron density at the base of the corona. The
correspondence of high and low density regions with regions of enhanced
and reduced emission in white light and Mgx pictures made during or
near the time of the eclipse are described.
---------------------------------------------------------
Title: Real Time Control of the Observing Program of an Orbiting
Solar Observatory
Authors: Reeves, E. M.; Huber, M. C. E.; Withbroe, G. L.; Noyes, R. W.
1971IAUS...41..336R Altcode:
No abstract at ADS
---------------------------------------------------------
Title: OSO-VI: Surges, Flares, and the Development of Active Regions
Authors: Reeves, E. M.; Dupree, A. K.; Goldberg, L.; Huber, M. C. E.;
Noyes, R. W.; Parkinson, W. H.; Withbroe, G. L.
1970BAAS....2R.215R Altcode:
No abstract at ADS
---------------------------------------------------------
Title: OSO-VI: The EUV Spectrum of Solar-Active Regions
Authors: Dupree, A. K.; Goldberg, L.; Huber, M. C. E.; Noyes, R. W.;
Parkinson, W. H.; Reeves, E. M.; Withbroe, G. L.
1970BAAS....2..191D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: OSO-VI: The Harvard Experiment
Authors: Huber, M. C. E.; Dupree, A. K.; Goldberg, L.; Noyes, R. W.;
Parkinson, W. H.; Reeves, E. M.; Withbroe, G. L.
1970BAAS....2S.200H Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Solar-blind photoelectric detection systems for satellite
applications.
Authors: Macar, P. J.; Rechavi, J.; Huber, M. C. E.; Reeves, E. M.
1970ApOpt...9..581M Altcode:
No abstract at ADS
