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The Quiescent Spectrum of 2S1636-536

King, A.; Turner, M. J. L.; Breedon, L. M. +1 more

During the EXOSAT observation of 2S1636-536 in July 1983 the quiescent flux was observed to brighten from 1.7×10 ^-9 ergs/cm. ² /sec to 2.6×10^-9 ergs/cm. ² /sec, this increase being accompanied by a decrease in effective temperature. Further analysis of the spectrum reveals that the best fit is a power …

The Golactic Gamma-Ray Distribution and the Radial Cosmic Ray Gradient

Harding, A. K.; Stecker, F. W.

The authors have derived the radial distribution of gamma-ray emissivity and the cosmic ray intensity in the Galaxy using the final SAS-2 results, the recently corrected COS-B results, and recent CO surveys of the northern and southern galactic hemispheres. In addition to the "5 kpc ring" of enhanced emission, there is evidence for spiral features…

Inverse-Compton Gamma Rays in the Galaxy

Bloemen, J. B. G. M.

Compton gamma rays with energies 1 MeV largely results from scattering between electrons, with energies 100 MeV, and photons in the optical and infrared range and the 2.7 K universal blackbody radiation. An empirical model of the inverse Compton (IC) gamma ray production in the Galaxy is presented, using the most recent estimate of the interstella…

EXOSAT observation of the QSO galaxy pair 1E0104.2+3153

Giommi, P.; Maccacaro, T.; Gioia, I. M.

A very long (160,000 second) observation of the X-ray source 1E0104.2+3153 was carried out using the Channel Multiplier Array (CMA) instrument on board Exosat in August 17, 1984. A thin Lexan filter having maximum throughput in the 0.05-2.0 keV CMA band was used during the entire observation period. The positional accuracy of the CMA was sufficien…

X-ray and optical variability at the hour timescale for 1E 0630+178 (GEMINGA) and its proposed optical couterpart

Caraveo, P. A.; Bignami, G. F.; Vigroux, L. +3 more

Einstein and EXOSAT data on the soft X-ray source IE 0630+178, the proposed counterpart of the γ-ray source GEMINGA, are analyzed for variability on the time scale of one to three hours. The EXOSAT September 1983 data, with an uninterrupted strech of over 10 hours offer the most interesting case. In parallel, a similar analysis is presented for th…

Optical and X-ray observations of 4U2129+47/V1727 CYG in a quiescent state

Pietsch, W.; Gottwald, M.; Steinle, H.

We observed the 5.2 h X-ray binary 4U2129+47 for more than one orbital cycle on 29 September and 4 October 1983 using the LE, ME and GSPC detectors of the ESA X-ray satellite EXOSAT. In neither detector an X-ray flux from the source could be detected. Quasi-simultaneous UBV observations using the 2.2 m telescop at the German-Spanish Astronomical C…

EXOSAT observations of active stellar coronae in the Cygnus Loop, T Tau & NGC 2264 regions

Mukai, K.; Charles, P. A.; Kahn, S. M. +4 more

A highly variable point X-ray source, first seen by the Einstein IPC, has been positioned with the EXOSAT CMA and identified with a bright (V = 8.5) K0 star. Although in the direction of the southern half of the Cygnus Loop, this star is almost certainly a foreground object and typical of other active cool stars that are related to RS CVn systems.…

Photometric calibration and first results obtained with the UFT experiment on board the astron satellite

Petrov, P.; Hua, C. T.; Courtes, G. +7 more

The UV telescope of 30 cm diameter equipped with a three channel scanner spectrometer aboard the highly eccentric orbit space station ``ASTRON'' is described

Absolute calibration of the whole device is performed using spectra of standard stars, of which absolute values were obtained by TDI or IUE experiments. Several photometric controls have…

X-ray astronomy in the EXOSAT ERA

Peacock, A.

Among topics discussed are: X-ray observations of stellar coronae and isolated white dwarfs; cataclysmic variables; and low/mass and high/mass X-ray binary sources. Consideration is also given to: supernova remnants and X-ray emission in the interstellar medium; active galactic nuclei; galaxy clusters; and X-ray scattering by intergalactic dust. A…

The Electron Spectra in the Synchrotron Nebula of the Supernova Remnant G 29. 7 - 0. 3

Braun, R.; Koch-Miramond, L.; Rocchia, R. +2 more

EXOSAT results obtained with the imaging instrument (CMA) and the medium energy proportional counters (ME) are discussed. Assuming that the featureless power-law spectrum obtained in the 2 to 10 keV range is synchrotron radiation from relativistic electrons, one derives constraints on magnetic field strength and age of the nebula. The energy spect…