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Hipparcos: Revised mission overview
Perryman, M. A. C.
The Hipparcos astrometry satellite was launched on 8 August 1989, and after spacecraft and payload commissioning, commenced the routine data acquisition phase on 26 November 1989. Having failed to reach its planned geostationary orbit, major revisions in the mission operations had to be performed, although the impact on the final mission accuracie…
Erratic profiles of type II bursts of very low fluence from the rapid burster.
Lewin, Walter H. G.; van Paradijs, Jan; Lubin, Lori M. +2 more
Results are presented of approximately 17 hr of Exosat observations of the Rapid Burster in September 1985 during which about 541 type II bursts lasting less than 30 s were observed. Although these bursts are known to have an approximately time-invariant profile showing successive peaks in the burst's decay portion, most of the 20-s bursts at the …
Optical and Ultraviolet Spectroscopy of Three F + B Binary Stars
Parsons, Sidney B.; Dempsey, Robert C.; Bopp, Bernard W.
Optical and ultraviolet spectroscopy is presented for three F + B objects that are members of the first group of strongly interacting, F II + B systems. The data obtained confirm that HD 59771, HD 242257, and CoD -30 5135 are all binary star systems consisting of a luminous F-type component and a B star. Strong, variable H-alpha emission is seen i…
Winds in central stars of planetary nebulae.
Patriarchi, P.; Perinotto, M.
Planetary Nebula with a Peculiar Spectrum in the Ultraviolet - CN:3-1
Gurzadian, G. A.; Terzian, Yervant; Egikian, A. G.
We have obtained IUE ultraviolet spectra of the low-excitation planetary nebula CN 3-1. The recordings show the well-known doublet 2800 MgII and resonance line 2852 MgI as strong absorption lines. We show that these lines cannot be of interstellar origin and that they may be formed in two envelopes surrounding the main nebula: in the transition zo…
Energetic water group ion fluxes (EH2O greater than 60 keV) in a quasiperpendicular and a quasiparallel shock front as observed during the Giotto-Halley encounter
Neubauer, F. M.; Daly, P. W.; Wenzel, K. -P. +5 more
Energetic water-group ions recorded by the Energetic Particle Analyzer/Energetic Particle Onset Admonitor (EPA/EPONA) and the Johnstone Plasma Analyzer (JPA) experiment aboard Giotto, as well as corresponding magnetic field measurements obtained, especially at the quasi-perpendicular inbound and quasi-parallel outbound bow shocks of Comet Halley, …
Groundbased optical and radio astrometry of Hipparcos extragalactic link objects
Zacharias, N.; Johnston, K. J.; de Vegt, Chr.
The construction of a new extragalactic all-sky reference frame based on groundbased high precision optical and radio astrometry of selected compact radio sources and radio stars has been started in 1987 as a joint longterm project involving several astrometric facilities in both hemispheres. At present this system is based on a masterlist of abou…
X-ray spectrum of the radio-loud quasar PKS 1217+023.
Ghosh, K. K.; Soundararajaperumal, S.
A study of the X-ray (0.1-10 keV) spectrum from the radio-loud quasar, PKS 1217+023 is presented. This quasar was observed with EXOSAT on two epochs in 1984 January 29 and May 14. The data were obtained from the EXOSAT archives. The soft (0.1-2 keV) and hard (2-10 keV) X-ray fluxes have displayed significant changes between the two observations. T…
EXOSAT observations of the quasar PKS 2135-147
Singh, K. P.; Rao, A. R.; Vahia, M. N.
A study of X-ray emission from the low polarization quasar, PKS 2135-147 (PHL 1657), is presented based on the EXOSAT observations carried out on two occasions separated by a week in 1984. There is little evidence for any variations in the X-ray intensity on hourly time scales during either of the two observations. About 30% change in the soft X-r…
A line identification study of the IUE SWP high dispersion spectrum of the UV-bright star Barnard 29 of Messier 13.
Leckrone, D. S.; Cacciari, C.; Adelman, S. J.
A line identification study was performed of the coaddition of three SWP high dispersion IUE exposures of the UV-bright star Barnard 29 of Messier 13. One of these images took two IUE shifts. The previous study by de Boer and Savage (1983) was extended and stellar lines of C I, C II, C III, C IV, N I, N III, O I, O III, O IV,Al III, Si II, Si III,…