Author name code: huber ADS astronomy entries on 2022-09-14 =author:"Huber, M.C.E." OR =author:"Huber, Martin C.E." ------------------------------------------------------------------------ Title: Spectroradiometry with space telescopes Authors: Pauluhn, Anuschka; Huber, Martin C. E.; Smith, Peter L.; Colina, Luis Bibcode: 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. 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. Bibcode: 2013opsg.book.....H Altcode: No abstract at ADS 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. Bibcode: 2013ops..book.....H Altcode: No abstract at ADS Title: The Role of Harvard College Observatory and UVCS in the Development of SOHO Authors: Huber, M. C. E. Bibcode: 2010ASPC..428...15H Altcode: No abstract at ADS Title: Introduction Authors: Huber, Martin C. E.; Treumann, Rudolf A. Bibcode: 2010png..book....1H Altcode: No abstract at ADS Title: Observing Photons in Space Authors: Huber, Martin C. E.; Pauluhn, Anuschka; Timothy, J. Gethyn Bibcode: 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. 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. Bibcode: 2010png..book.....E Altcode: No abstract at ADS Title: Calibration Authors: Huber, Martin C. E.; Pauluhn, Anuschka; Timothy, J. Gethyn; Zehnder, Alex Bibcode: 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. Title: Postscript Authors: Huber, Martin C. E.; Pauluhn, Anuschka; Culhane, J. Len; Timothy, J. Gethyn; Wilhelm, Klaus; Zehnder, Alex Bibcode: 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. Title: Introduction Authors: Huber, Martin C. E.; Treumann, Rudolf A. Bibcode: 2009SSRv..148....1H Altcode: 2010SSRv..tmp...19H No abstract at ADS Title: Lessons from Introducing New Scientific Disciplines Into European Space Research Authors: Huber, Martin C. E. Bibcode: 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. Title: Lessons from Introducing New Scientific Disciplines Into European Space Research Authors: Huber, Martin C. E. Bibcode: 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.

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. Title: Introduction (3) Authors: Huber, M. C. E. Bibcode: 2006ESASP.637E...4H Altcode: 2006ESASP.637....4H; 2006bept.confE...4H No abstract at ADS Title: SOHO in Venice Authors: Huber, M. C. E. Bibcode: 2006ESASP.617E..31H Altcode: 2006soho...17E..31H No abstract at ADS Title: Opening remarks (Solar variability: from core to outer frontiers) Authors: Huber, Martin C. E. Bibcode: 2002ESASP.506D..23H Altcode: 2002ESPM...10...23H; 2002svco.confD..23H No abstract at ADS Title: A Delayed but Ultimately Successful Return Authors: Huber, Martin C. E. Bibcode: 2002ESASP1261..109H Altcode: 2002ses..book..109H No abstract at ADS Title: The scientific achievements of Klaus Wilhelm Authors: Huber, Martin C. E. Bibcode: 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. 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. Bibcode: 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. Title: The radiometric calibration and intercalibration of SOHO Authors: Huber, M. C. E.; Pauluhn, A.; von Steiger, R. Bibcode: 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. Title: Foreword Authors: Pauluhn, A.; Huber, M. C. E.; von Steiger, R. Bibcode: 2002ISSIR...2D...7P Altcode: 2002ESASR...2D...7P; 2002rcs..confD...7P No abstract at ADS Title: The Radiometric Calibration of SOHO Authors: Pauluhn, A.; Huber, M. C. E.; von Steiger, R. Bibcode: 2002ISSIR...2.....P Altcode: 2002ESASR...2.....P; 2002rcs..conf.....P No abstract at ADS 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. Bibcode: 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. Title: The Century of Space Science, Volume I Authors: Bleeker, Johan A.; Geiss, Johannes; Huber, Martin C. E. Bibcode: 2002css1.book.....B Altcode: No abstract at ADS Title: Foreword Authors: Pauluhn, A.; Huber, M. C. E.; von Steiger, R. Bibcode: 2002ISSIR...2D...5P Altcode: 2002ESASR...2D...5P; 2002rcs..confD...5P No abstract at ADS Title: Spectroradiometry for Solar Physics in Space Authors: Smith, P. L.; Huber, M. C. E. Bibcode: 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. 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. Bibcode: 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. 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. Bibcode: 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 %. Title: The century of space science Authors: Bleeker, J. A. M.; Geiss, J.; Huber, M. C. E. Bibcode: 2002css1.book....3B Altcode: No abstract at ADS Title: Roger Bonnet, the scientist Authors: Huber, Martin C. E. Bibcode: 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. 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. Bibcode: 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. Title: Gravitation II: The LISA Cornerstone Authors: Huber, M. C. E. Bibcode: 2001ESASP.469...43H Altcode: 2001fpsr.conf...43H No abstract at ADS 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. Bibcode: 2001ASPC..223..721P Altcode: 2001csss...11..721P No abstract at ADS Title: Preface Authors: Huber, M. C. E.; Jacob, M. Bibcode: 2001ESASP.469....1H Altcode: 2001fpsr.conf....1H No abstract at ADS Title: Introduction Authors: Huber, M. C. E. Bibcode: 2001ESASP.454...11H Altcode: 2001mrap.conf...11H No abstract at ADS Title: Fundamental Physics in Space and Related Topics Authors: Huber, M. C. E.; Jacob, M.; Battrick, B. Bibcode: 2001ESASP.469.....H Altcode: 2001fpsr.conf.....H No abstract at ADS 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. Bibcode: 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 ~ 104 K) indicating a small relative redshift. With respect to the rest wavelength, however, only lines formed above 5 * 105 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 105 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. Title: Welcome Address Authors: Huber, M. C. E. Bibcode: 2000ESASP.445....3H Altcode: 2000sfsl.conf....3H No abstract at ADS 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. Bibcode: 2000IAUTA..24...77V Altcode: No abstract at ADS 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. Bibcode: 2000Metro..37..393W Altcode: No abstract at ADS 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. Bibcode: 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 * 104 K), the transition region O V 629.7 Ä (2.5 * 105 K) and coronal Mg IX 368.1 Ä (106 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. Title: Alan Gabriel-A Career between Spectroscopy and the Sun Authors: Huber, M. C. E. Bibcode: 1999ESASP.446....9H Altcode: 1999soho....8....9H No abstract at ADS 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. Bibcode: 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. Bibcode: 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, H0, and O5+, as well as the outflow velocity and unresolved anisotropic most probable speeds for H0 and O5+. 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 H0 atoms and O5+ 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 Rsolar, the observed transverse most probable speeds for O5+ are significantly larger than the corresponding motions for H0, and the outflow velocities of O5+ are also significantly larger than the corresponding velocities of H0. 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. Bibcode: 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. Bibcode: 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 105 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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 Bibcode: 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. Bibcode: 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, H0, and O5+ and the outflow velocity and unresolved most probable velocities for H0 and O5+ 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 H0 atoms and O5+ 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 Rsolar, the observed transverse, most probable speeds for O5+ are significantly larger than the corresponding motions for H0, and the outflow velocities of O5+ are also significantly larger than the corresponding velocities of H0. We discuss the constraints and implications on various theoretical models of coronal heating and acceleration. Title: Introduction Authors: Huber, M. C. E. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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⊙ (solar radius) from the center of the disk. We find the electron temperatures, Te, to be less than 800,000 K in a plume in the range from r = 1.03 to 1.60 R⊙, 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 (ΔλD ~ 150 mÅ, v1/E ~ 43 km s-1) than in interplume lanes (~190 mÅ, ~55 km s-1). The thermal and turbulent ion speeds, v1/E, of Si7+ reach values up to ~80 km s-1 in the darkest regions outside plumes above the coronal hole. This corresponds to a kinetic ion temperature of 1 × 107 K. A limit of ~18 km s-1 for the bulk speed in plumes below r = 1.2 R⊙ is deduced from O VI line shift measurements and consideration of the three-dimensional plume geometry (differential line-of-sight velocities <=3 km s-1), whereas differential line-of-sight velocities of Mg8+ ions up to 34 km s-1 can be seen in dark regions. Title: Foreword Authors: Fröhlich, C.; Huber, M. C. E.; Solanki, S. K.; von Steiger, R. Bibcode: 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. Bibcode: 1998sce..conf.....F Altcode: No abstract at ADS Title: Future Mission Possibilities Within ESA Authors: Huber, M. C. E.; Coradini, M. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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 Rsolar. 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-1 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. Bibcode: 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. Bibcode: 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. Bibcode: 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 H0, O5+, Mg9+, and Fe11+ velocity distributions and initial indications of outflow velocities for O5+ are described. In streamers, the H0 velocity distribution along the line of sight (specified by the value at e-1, along the line of sight) decreases from a maximum value of about 180 km s-1 at 2 R⊙ to about 140 km s-1 at 8 R⊙. The value for O5+ increases with height reaching a value of 150 km s-1 at 4.7 R⊙. In polar coronal holes, the O5+ velocity at e-1 is about equal to that of H0 at 1.7 R⊙ and significantly larger at 2.1 R⊙. The O5+ 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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 × 106 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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 104 to 2 × 106K 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. Bibcode: 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. Bibcode: 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. Bibcode: 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 103 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. Bibcode: 1995ESASP1179.....H Altcode: 1995rass.book.....H No abstract at ADS Title: Opening remarks Authors: Huber, Martin C. E. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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⊙. 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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 Bibcode: 1994ESASP1170.....B Altcode: 1994twse.conf.....B No abstract at ADS Title: Maintaining the Astronomical Environment for Space Astronomy Authors: Huber, M. C. E. Bibcode: 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. Bibcode: 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. Bibcode: 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.

The transition probabilities of 21 very weak lines have been used to derive a solar titanium abundance of αTi = log(NTi/NH) + 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. Bibcode: 1993BAAS...25.1209B Altcode: No abstract at ADS Title: Solar physics within ESA's planning. Authors: Huber, M. C. E. Bibcode: 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. Bibcode: 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 arcmin2 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. Bibcode: 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. Bibcode: 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. Bibcode: 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 Bibcode: 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. Bibcode: 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 104 and a few 106K. 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. Bibcode: 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 104 to more than 1.8×106K. 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. Bibcode: 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. Bibcode: 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. Bibcode: 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 Bibcode: 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 Bibcode: 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 Bibcode: 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 104 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-1), depending on the level of the accumulated signal. Title: Comet Nucleus Sample Return - Plans and Capabilities Authors: Huber, M. C. E.; Schwehm, G. Bibcode: 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. Bibcode: 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. Bibcode: 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 Bibcode: 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.

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.

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. Bibcode: 1991eua..coll..380M Altcode: No abstract at ADS Title: Transition probabilities from the 6s6p 1P°1 resonance level of neutral barium Authors: Bizzarri, A.; Huber, M. C. E. Bibcode: 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 1P°1 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. Bibcode: 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 Bibcode: 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. Bibcode: 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. Bibcode: 1990ebua.conf..263H Altcode: No abstract at ADS Title: ESA Astronomical projects Authors: Huber, M. C. E. Bibcode: 1990nwus.book..535H Altcode: No abstract at ADS Title: Opening Remarks Authors: Huber, M. C. E. Bibcode: 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. Bibcode: 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 1°1 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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 Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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 Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 1987ESASP.268..147H Altcode: 1987sass.conf..147H No abstract at ADS Title: Transition probabilities in neutral barium Authors: Niggli, S.; Huber, M. C. E. Bibcode: 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 1P° 1, 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. Bibcode: 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. Bibcode: 1987PAICz..65.....P Altcode: No abstract at ADS Title: Staff Movements Authors: Huber, M. C. E. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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 L1 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 2s23p 2P0 Term of Singly-Ionized Carbon Authors: Huber, M. C. E.; Sandeman, R. J.; Tozzi, G. P. Bibcode: 1984PhST....8...95H Altcode: 1984PhyS....8...95H The branching ratios of the 2s23p 2P01/2,3/2 levels of C+ 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. Bibcode: 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. Bibcode: 1983A&A...126..320T Altcode: The relative strengths of allowed and intercombination transitions out of the 3s3P0, 2p3 3P0 and 3D0, 3d3P0 and 3D0 as well as 4s3P0 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. Bibcode: 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. Bibcode: 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 cm2. Title: Solar physics from space. Proceedings of a conference held at ETH Zurich, November 11 - 14, 1980. Authors: Huber, M. C. E. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 1980fsoo.conf..146H Altcode: No abstract at ADS Title: Transition probabilities and their accuracy. Authors: Huber, M. C. E.; Sandeman, R. J. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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 5P20) to the ground level (a 7S3) as well as to excited terms (a 5S, a 5D). 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. Bibcode: 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. Bibcode: 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. Bibcode: 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 H2, He, O2, CO, and Kr for 168<=λ<=288 nm Authors: Smith, Peter L.; Huber, Martin C. E.; Parkinson, W. H. Bibcode: 1976PhRvA..13.1422S Altcode: Precision measurements of the refractivities of H2, He, O2, 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 H2, CO, and O2, 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 H2 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 H2, CO, and Kr. For O2 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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 104 to 3.5 × 106 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 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. Bibcode: 1970ApOpt...9..581M Altcode: No abstract at ADS