Search Publications
The ion mass spectrometer on Giotto
Schwenn, R.; Altwegg, K.; Balsiger, H. +18 more
The design of the Giotto ion mass spectrometer (IMS) system, its calibration, and the initial flight performance are discussed. The IMS system consists of two sensors: one optimized for the outer coma, the other for the inner coma, with each sensor obtaining complementary information in the region for which it was not optimized. Both sensors featu…
Detailed EXOSAT and optical observations of the intermediate polar 3A0729+103 : discovery of two medium energy X-ray emission regions.
McHardy, I. M.; Pye, J. P.; Fairall, A. P. +1 more
EXOSAT observations of the intermediate polar cataclysmic variable 3A0729+103 reveal a strong orbital modulation, with the 2 - 4 keV X-rays being significantly more modulated than the 4 - 6 keV X-rays, indicative of photoelectric absorption. Contemporaneous optical spectroscopy shows that the X-ray minimum occurs at maximum velocity of recession o…
The Low-Luminosity X-Ray Sources in Omega Centauri
Bolte, Michael; Margon, Bruce
The authors report multicolor CCD photometry of the fields of three X-ray sources in ω Centauri; two have very accurate (10arcsec) EXOSAT X-ray positions, in addition to observations from the Einstein Observatory. The crowding in these X-ray fields is moderate and does not preclude accurate photometry of individual objects. Although the data in th…
A search for X-ray emission from a nearby pulsar : PSR 1929+10.
Brinkmann, W.; Kiziloglu, U.; Oegelman, H. +2 more
The authors report observations of PSR 1929+10 with the EXOSAT observatory. In the 0.04 to 2.4 keV range a 2σ upper limit of 0.5×10-3cts s-1 was obtained. This translates to a luminosity upper limit of L ≤ 2×1029erg s-1 for a power-law source with photon number index α = 1 - 3, and L ≤ 1030erg…
Long-term variability of the far-UV high velocity components in gammaCas (1978-1986).
Doazan, V.; Thomas, R. N.; Rusconi, L. +2 more
A synthesis of the authors' long term observations of γ Cas in the visual and in the far UV, combined with IUE archived spectra, shows that: (1) The occurrence of the high velocity components observed in the Si IV, C IV, and N V resonance lines exhibits a long term variability pattern, which is associated with the cyclic V/R variations of the Balm…
The X-ray properties of 3A 1907+09.
Cook, M. C.; Page, C. G.
A series of EXOSAT observations of the high-mass X-ray binary 3A1907+09 in 1984 early June show a spin-down of the neutron star since the discovery of X-ray pulsations in 1983 September by Tenma. The mildly eccentric orbit derived from Tenma data is confirmed and orbital parameters are refined. The pulse-averaged spectra were consistent with a har…
X-Ray and Optical Observations of X-Ray--selected BL Lacertae Objects
Maccagni, D.; Giommi, P.; Garilli, B. +4 more
Results from several X-ray and optical observations of five X-ray-selected BL Lacertae objects are reported. X-ray light curves covering periods of up to 6 yr reveal that the X-ray flux from these objects does not show large-amplitude trends over this time scale. Variations of up to 2 mag have been observed in the optical. The soft X-ray spectra o…
Alfvenic Turbulence in the Solar Wind Flow during the Approach to Comet p/ Halley
Coates, A. J.; Winningham, J. D.; Thomsen, M. F. +8 more
The Johnstone Plasma Analyser on Giotto operated almost continuously for two days before the encounter with comet Halley. Throughout this period it made observations of the proton and alpha particle distributions in the solar wind with 8 seconds time resolution. As the comet was approached, fluctuations were observed in all the primary bulk parame…
An EXOSAT observation of 1.5 orbital cycles of the 0.7 day short-period RS CVn system ER Vul.
Parmar, A. N.; White, N. E.; Culhane, J. L. +1 more
Two Exosat observations of the short-period 0.7-day eclipsing RS Cvn binary system ER Vul are reported. The first observation in October 1984, lasted for 3 hr, while the second in May 1985, covered 1.5 orbital cycles. The overall counting rate decreased by a factor of about 2 in the 6 months separating the two observations. No strong orbital modul…
Photometry and spectroscopy of the eclipsing P Cygni star R 81 in theLarge Magellanic Cloud.
Stahl, O.; Zickgraf, F. -J.; Wolf, B.
IUE high resolution data of the LMC P Cyg star R 81 confirm that the wind characteristics of R 81 and P Cyg are very similar. Photometric monitoring from 1982 to 1986 revealed several brightness minima with a period of 74.59 days. It is concluded that R 81 is an eclipsing binary with this period. From the photometry and the period, a preliminary m…