Search Publications
An Ionized Accretion Disk in Cygnus X-1
Done, C.; Mulchaey, J. S.; Mushotzky, R. F. +1 more
Results of an analysis of archival Exosat and HEAO 1-A2 observations of Cyg X-1 are presented. It is found, in agreement with Ebisawa (1991), that the X-ray spectrum of Cyg X-1 exhibits a 'high-energy excess' above 8 keV, similar to that seen in Ginga spectra of AGN. It is shown, on the basis of a likelihood ratio test, that the data are significa…
Correlated Hard X-Ray and Ultraviolet Variability in NGC 5548
Nandra, K.; Clavel, J.; Reichert, G. A. +7 more
We present the result of a series of contemporaneous (within one day) hard X-ray (Ginga) and ultraviolet (IUE) observations of the Seyfert 1 galaxy NGC 5548. Nine of these observations were carried out over a period of 51 days in 1990 May-July, and two in 1989. An additional simultaneous IUE-EXOSAT observation obtained on 1984 May 21 is also analy…
EXOSAT X-Ray Spectra of Quasars
Comastri, Andrea; Setti, Giancarlo; Zamorani, Giovanni +4 more
We have measured the X-ray spectra in the 0.1-10 keV energy range for 17 AGNs (mostly PG quasars) using the EXOSAT Low and Medium Energy arrays. The sample has been selected on the basis of soft X-ray flux and includes all the AGNs in the 1981 Zamorani et al. and 1986 Tananbaum et al. publications with an Einstein flux greater than 6x10^-12^ ergs …
EXOSAT Observations of the Be/X-Ray Binary 4U 2206+54
Saraswat, Priyamvada; Apparao, Krishna M. V.
We present the X-ray observations of the Be star binary system 4U 2206 + 54 made with the EXOSAT satellite during the period 1983-1985. The observations were carried out on three occasions, each separated by roughly a year. The source was active during the 1983 and 1985 observations and several short duration flares were observed. The spectrum, du…
X-Ray Observations of Planetary Nebulae with Binary Nuclei
Nousek, J. A.; Apparao, K. M. V.; Berthiaume, G. D.
Einstein and EXOSAT satellite observations of X-ray emission from the planetary nebulae A63 and LoTr 5 are reviewed. Both of these systems contain binary central stars. No flux was detected from A63 (central star UU Sge). LoTr 5 (central star IN Com) is a previously unreported X-ray emitter; it showed no statistically significant X-ray variability…
EXOSAT Observations of the X-Ray Binary Pulsar 4U 1538-52
Cusumano, G.; Frontera, F.; Orlandini, M. +2 more
Results are reported from a temporal and spectral analysis performed on four EXOSAT observations, part of which were taken from the EXOSAT archive, carried out during March and August 1984. In the first observation an absorbing episode was detected, which may be attributed to an inhomogeneity in the stellar wind of QV Nor; the scale height of this…
X-Ray Observations of the Seyfert 1 Galaxy MCG 2-58-22
Ghosh, K. K.; Soundararajaperumal, S.
Results of the detailed X-ray (0.1-10 keV) spectral analysis of the Seyfert 1 galaxy, MCG 2-58-22, are presented based on the EXOSAT observations on 1984 November 16-26. X-ray spectra of this source were obtained from the EXOSAT archives. Weak, soft flux (0.1-2 keV) variations were found on time scales of 2-3 days, and no variations of the hard fl…
EXOSAT Observations of the Broad-Line Radio Galaxy 3C 382
Ghosh, K. K.; Soundararajaperumal, S.
X-ray observations of the broad-line radio galaxy 3C 382 were carried out with EXOSAT on many occasions (>20) between 1983 and 1985. Low and Medium Energy (LE and ME) spectra of this source were obtained from the EXOSAT data base. The hard-X-ray luminosity light curve of 3C 382 which was constituted from Ariel V, HEAO 1, Einstein, EXOSAT, and G…
X-Ray Continuum and Line Emission of the Seyfert Galaxy MCG-5-23-16
Singh, K. P.; Rao, A. R.; Vahia, M. N.
We report observations of X-ray continuum and line emission from the highly absorbed and variable Seyfert galaxy MCG -5-23-16, using the low- energy and the medium-energy detectors of the EXOSAT Observatory. The galaxy was observed in 1983 December and in 1984 May. The X-ray intensity of the source is observed to vary by ~25% in the hard (2-10 keV…