Search Publications
A High Quality Low State Observation of CIRCINUS-X-1
Tennant, A. F.
Cir X-1 was extremely faint when we observed it with EXOSAT. The light curve clearly shows the source in two states; a faint variable state and a very faint but more constant state. The spectrum is very complicated but clearly shows the existence of an iron line.
HR 5637 : the unveiling of a binary.
Cottrell, P. L.; Ake, T. B., III; Noordanus, B.
HR 5637, previously classified as G1/3 Ib/II but considered composite by Bidelman and MacConnell, has been examined both photometrically and spectroscopically. The spectroscopic observations spanned the wavelength interval 1000-7000 A. Using these data in various combinations, the star is shown to be a binary with components of G2-5Ib and B8 V, wi…
Is cygnus X-3 a low-mass X-ray binary?
van der Klis, M.; Jansen, F.
We present examples of the quasi-periodic variations in the X-ray flux of Cyg X-3 which we have recently found during observations of this source with EXOSAT. Amplitudes and periods of the variations range from 5% to 20% of the total flux and from 50 to 1500 s, respectively. Our tentative interpretation of these quasi-periodicities, the occurrence…
EXOSAT Observations of the Contact Binary Vw-Cephei
Heise, John; Vilhu, Osmi
EXOSAT observations of the contact binary VW Cephei on 19th March 1984 are presented. The L1-telescope with CMA+thick Lexan filter was used. The observations cover one orbital revolution showing an asymmetrical X-ray light curve. This can be modelled by an active neck, connecting the two stars, and with enhanced coronal regions on the primary star…
MR2251-178: Preliminary results of an X-ray monitoring programme
Pounds, K. A.; Stewart, G. C.; Stanger, V. A.
We present the initial results from an X-ray monitoring programme of the bright QSO MR2251-178.
Search for millisecond rotational periods in some low-mass X-ray binaries observed by EXOSAT
Sztajno, M.; Truemper, J.; Langmeier, A.
We present the results of a search for millisecond rotational pulsations in the X-ray emission of five low-mass X-ray binaries: MXB1728-34, 4U1702-42, 4U1705-44, 4U1755-33 and GX17+2. The data were obtained by the EXOSAT Medium Energy Experiment Argon Counters (1-20 keV) with a time resolution of 7.8125 milliseconds. We searched for periods in the…
EXOSAT Observations of the Bl-Lacertae Object MKN421
McHardy, I.; Warwick, R. S.; Pounds, K. A.
The BL Lac object Mkn 421 was observed by EXOSAT four times over a period of six days in February 1984. Significant X-ray variability was apparent on a timescale of less than a day, but with no accompanying spectral change. The source exhibited a very soft power law X-ray spectrum with an extremely low intrinsic column density (NH≲10
Observations of Comet Crommelin. V - Anomalous hydrogen source
Wallis, M. K.; Carey, W. C.
Lyman-alpha intensities measured by IUE at various positions in the coma of Comet Crommelin are interpreted on the basis of H2O model calculations. However, the H-production on dates in March and April 1984 was significantly higher than implied by OH measurements by IUE and from the ground. Simultaneous data from the two apertures on March 30 excl…
X-Ray Optical and Ultraviolet Observations of the Am-Herculis System E2003+225
Mukai, K.; Maraschi, L.; Chiappetti, L. +13 more
The AM Her type object E2003+225 was observed with EXOSAT, IUE and ground-based telescopes on 1983 Oct. 12. The brightness of the ultrasoft X-ray component allowed the Objective Grating Spectrometer (OGS) to be used, which gave a model-independent determination of the temperature of the blackbody spectrum. The star was observed again on 1984 July …
The Discovery of a 25-MIN Regular Modulation in the X-Ray Flux from 2S0142+61
Parmar, A. N.; White, N. E.; Giommi, P. +2 more
A 13 hr observation of 2S0142+61 on 1984 August 27 by EXOSAT shows the X-ray flux of 2S0142+61 to be modulated with a period of 1456+/-6 s. The 1 10 keV spectrum is two component with a ∼0.7 keV thermal and 0.0 energy index power law, with 30% of the total luminosity in the thermal component. The spectrum is absorbed by ∼1 × 1022 H cm