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GX 339-4 : EXOSAT observations in the off and soft states.
Chiappetti, L.; Motch, C.; Ilovaisky, S. A. +1 more
Exosat observations of the highly variable low-mass X-ray binary GX 339-4, obtained with the low-energy telescope and channel-multiplier array in the off state on Apr. 25, 1985, and with the medium-energy Ar proportional counters and collimator array in the off state in Apr. 29, 1985, and in the soft state on May 7, 1984, are reported. The data ar…
EXOSAT detection of an X-ray flare from the solar type star pi 1 UMa.
Piro, L.; Landini, M.; Pallavicini, R. +1 more
An X-ray flare has been detected on the G0 dwarf star π1UMa using the European satellite EXOSAT. With the exception of the Sun, this is the first time that an X-ray flare has been observed in a normal solar-type star, which is not a member of a binary system and is not a classical flare star. As a member of the Ursa Major Cluster, π
The optical and X-ray decline of V 0332+53 (X 0331+53, BQ Cam).
van der Klis, M.; Charles, P. A.; Corbet, R. H. D.
The authors present optical spectra of the X-ray transient V 0332+53 (BQ Cam). The equivalent width of the Hα emission line in the spectrum has declined by a factor ≡2 compared with previous observations. This is interpreted as showing that V 0332+53 is surrounded by an evolving circumstellar envelope. EXOSAT observations failed to detect X-ray em…
Optical and X-ray observations of 4U 2129+47/V1727 CYG in an extended quiescent state.
Pietsch, W.; Gottwald, M.; Graser, U. +1 more
Observations of the 5.h2 h X-ray binary 4U2129 + 47/V1727 Cyg for more than one orbital cycle on September 29 and October 4, 1983 with the ESA X-ray satellite EXOSAT failed to detect the source in the low and medium X-ray energy band. Quasi-simultaneous UBV photometry using the 2.2 m telescope at the German-Spanish Astronomical Center, …
The soft X-ray superoutburst of VW Hydri.
Heise, J.; van der Woerd, H.; Bateson, F.
The dwarf nova VW Hyi has been monitored with Exosat, during and shortly after the optical superoutburst of November 1983. VW Hyi appears to be a very soft X-ray emitter, and is marginally detected in the hard (1 to 6 keV) X-ray range. The soft X-ray emission increased by two orders of magnitude during outburst, with the dominant emission at wavel…
EXOSAT observations of GX 304-1 in an X-ray of state.
Pietsch, W.; Kahabka, P.; Gottwald, M. +2 more
Three EXOSAT observations of the Be/neutron star X-ray binary system GX 304-1 in July/August 1984 around the time of an expected periodic outburst occurring at 132.5 d intervals showed no detectable flux of X-rays. The derived upper limits of the flux in the low and medium energy range (0.03 - 2.4 keV and 2 - 6 keV) are both 3×10-12erg …
Wide-band X-ray observations of MK 501.
Ubertini, P.; Bazzano, A.; Brunner, H. +3 more
The BL Lacertae object MK 501 was observed by EXOSAT on 25 July 1984 for 3.65 hours. The data from the low energy (LE) and medium energy (ME) instruments suggest a single power law spectrum over the energy range 0.04 - 8 keV with a photon index of 2.5±0.1, an intensity at 1 keV of 0.022±0.003 photons/cm2s keV and a column density consis…
A soft X-ray observation of ω Centauri with EXOSAT.
van Paradijs, J.; Jansen, F.; Verbunt, F. +2 more
In an observation with the LE1 CMA detector of the EXOSAT observatory the authors have detected two of the X-ray sources previously discovered in the globular cluster ω Cen with the IPC detector on board of the Einstein satellite. They give improved positions for these two sources. On the basis of comparison of the EXOSAT and Einstein count rates …