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Optical spectra of dzeta Aurigae systems. IV. The January 1990 eclipse ofHR 2554 : detection of chomospheric absorption and extended plasma at 10 5 K.
Schroeder, K. -P.; Huensch, M.
Eclipse observations of HR 2554 are presented. These observations were obtained simultaneously during the January 1990 eclipse with ESO telescopes and the IUE satellite. Chromospheric absorption and changes in the circumstellar matter were investigated. Improved system parameters were derived from the light curve. For each of the composite spectra…
HIPPARCOS great-circle reduction - Theory, results and intercomparisons
van der Marel, Hans; Petersen, Carsten
In this paper some of the results of the great-circle reduction in the two data reduction consortia (NDAC and FAST) are presented. It is shown that the root-mean-square (rms) error of the great-circle abscissa of stars brighter than 10 mag is between 3-5 milli-arcsec. This is as was expected before launch, even in spite of the fact that the data-s…
IUE observations of H Lyman-α in comet P/Giacobini-Zinner
Feldman, Paul D.; Combi, Michael R.
Comet P/Giacobini-Zinner (1985 XIII) was observed during the flyby of the International Cometary Explorer (ICE) satellite and during the 3 preceding months by the International Ultraviolet Explorer (IUE) satellite. Models for the hydrogen abundance and spatial distribution, which were previously used to reproduce the observed spatial distribution …
The interrelation of UV and optical activity diagnostics in HK Lacertae.
Houdebine, E. R.; Butler, C. J.; Olah, K. +3 more
The study examines and compares optical photometric and UV (IUE) spectroscopic data on the active RS CVn star HK Lac gathered in the years 1979, 1980, and 1987. The photometry is modeled by representations of 'starspots' and, in general, it is found that the UV emission lines are stronger at times of spot maximum. The variable interstellar absorpt…
Predictions of the solar wind interaction with Comet Grigg-Skjellerup
Coates, A. J.; Johnstone, A. D.; Huddleston, D. E.
The planned encounter of the Giotto spacecraft with comet Grigg-Skjellerup on 10th July 1992 promises to extend our knowledge of the solar wind interaction with comets substantially. While there have been spacecraft missions to comets before now, this mission is exploratory in the sense that the target comet is much older and therefore it has a mu…
An Overview of Energetic Particle Measurements in the Jovian Magnetosphere with the EPAC Sensor on Ulysses
Krupp, N.; Woch, J.; Keppler, E. +5 more
Observations of ions and electrons of probable Jovian origin upstream of Jupiter were observed after a corotating interplanetary particle event. During the passage of Ulysses through the Jovian bow shock, magnetopause, and outer magnetosphere, the fluxes of energetic particles were surprisingly low. During the passage through the "middle magnetosp…
X-ray observations of flat spectrum radio sources with the HEAO-A, Einstein and EXOSAT observatories.
Pietsch, W.; Schaaf, R.; Witzel, A. +3 more
This paper presents X-ray data collected with the satellites HEAO-A, EINSTEIN (HEAO-B) and EXOSAT for flat spectrum radio sources. Most of the sources are from a complete sample of the high-declination 5 GHz survey.
The hot subdwarf in the eclipsing binary HD 185510.
Simon, Theodore; Jeffery, C. S.; Evans, T. L.
High-resolution spectroscopic measurements of radial velocity are employed to characterize the eclipsing binary HD 185510 in terms of masses and evolutionary status. The IUE is used to obtain the radial velocities which indicate a large mass ratio Mp/Ms of 7.45 +/- 0.15, and Teff is given at 25,000 +/- 1000 K based on Ly alpha and UV spectrophotom…
Spectroscopic binary orbits from ultraviolet radial velocities. Paper 10: CW Cephei (HD 218066)
Stickland, D. J.; Koch, R. H.; Pfeiffer, R. J.
Observations of CW Cephei were carried out repeatedly in the course of three days in December 1991, using the high-resolution, short-wavelength spectrograph of IUE, with an additional spectrum taken on February 6, 1992. The paper presents a log of these observations, which represent the only high-resolution observations of this star in the archive…
Binary Star Observations With the Hubble Space Telescope Fine Guidance Sensors. II. Bright Hyades
Franz, O. G.; Nelan, E.; Lattanzi, M. G. +3 more
The paper reports on astrometric measurements performed with the Hubble Space Telescope fine guidance sensors in the transfer scan mode on selected bright member stars of the Hyades cluster. The purpose of these measurements was to quickly validate this mode of operation of the fine guidance sensors - in the presence of many optical anomalies - an…