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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…
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.…
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…
X-Ray Spectrum of the TYCHO SNR Observed with EXOSAT
Robba, N. R.; Taylor, B. G.; Morini, M. +2 more
The Gas Scintillation and Medium Energy instruments onboard EXOSAT measured the continuum and line emission spectrum in the Tycho supernova remnant. For the first time the iron line at 6.53 keV is clearly resolved from the continuum, in addition to the lines from S, Ar and Ca. The comparison with a non-equilibrium ionisation model (Hamilton et al …
EXOSAT results on the X-ray burster 2S 1254-690.
Parmar, A. N.; Courvoisier, T. J. -L.; Peacock, T.
Exosat observations of 2S1254-690 in August 1984 have confirmed the presence of periodic dips in the X-ray intensity. These dips occurred with a period of 3.9 hours and lasted for about 50 minutes. During individual dips, the observed X-ray flux oscillated several times between the quiescent level and an undetectable level on time scales varying f…
Gamma-Ray Sources Observed by Cos-B
Hermsen, W.
The nature of the fine-scale structure in the gamma-ray distribution is not yet disclosed. Considerable debate is going on whether these structures which appear point-like in the data, are mainly diffuse in nature or are genuinely compact objects. Most of the uncertainty is due to the experimental limitations. A status report is presented on the e…
Observations of Supernova Explosions and Cosmic-Rays
Palumbo, G. G. C.
A summary of coordinated observations at various frequencies of two type II and three type I SNe is given. Since type II events emit radio and X-ray radiation in the early phases it is shown how one has data to estimate the Cosmic Ray output from these SNe.
The Use of Gamma-Rays to Trace the Local Interstellar Hydrogen
Strong, A. W.
COS-B data in the latitude range 11° <¦b¦ < 19° show the gamma-ray intensity to be closely correlated with the total line-of-sight absorption derived from galaxy counts. It is found that to a good approximation the gamma-ray intensity is proportional to the total gas column density, and on this basis a map of the angular distribution of loca…
3C273 - a Review of Recent Results
Ulrich, M. -H.
3C 273 is the most extensively studied quasar both from the ground and from space. Recent satellite observations have given important information on the overall electromagnetic spectrum of 3C 273 in the γ-ray, X-ray, and UV ranges. The most salient results are: (i) the energy per decade of frequency emitted by 3C 273 is nearly constant between 600…
Ultraviolet and Optical Observations of HDE245770 / A:0535+26 System during an X-Ray Flare
Giovannelli, F.; Persi, P.; Bartolini, C. +4 more
We present high and low dispersion UV spectra of HDE 245770, which is the optical counterpart of the recurrent transient X-ray pulsar A 0535+26,during a decay of an X-ray flare. UBV photometric measurements and medium dispersion optical spectra were simultaneously obtained. The energy distribution of the star in the 12 10 micron range is compared …