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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…
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…
Dust emission of Comet Halley at large heliocentric distances
Gruen, E.; Schwehm, G.; Massonne, L. +2 more
Comet Halley is currently approaching the inner solar system. Four spacecrafts (NASA's spacecraft, two Russian Vega probes and the Japanese MS-T5 spacecraft) have already been launched to encounter the comet in March 1986. Two additional Halley probes (the European Giotto spacecraft and another Japanese Planet-A probe) will be launched in mid-85 t…
Einstein and EXOSAT observations of geminga (1E0630+178). A summary of the short - and medium - term variability data
Caraveo, P. A.; Bignami, G. F.; Mereghetti, S. +1 more
The X-ray source 1E 0630 + 178 was discovered by Bignami et al. (1983) during an X-ray survey. The survey was conducted with the aid of the Einstein Observatory. The involved field was also observed with the Exosat satellite in September 1983, when both Low Energy telescopes were still operating. The Einstein and Exosat data bases were utilized in…
EXOSAT- Present Status and Future Prospects
Redfern, R. M.
The design and operation of the ESA Exosat orbiting X-ray observatory (launched in May 1983) are reviewed, and some preliminary results are summarized. The value of X-ray observations for investigating hot sources assumed to be driven by accretion into neutron stars is indicated; the low-energy imaging telescopes, medium -energy experiment, and ga…
Abondances NLTE de Ca, Mg, C, Si dans quelques étoiles A.
Freire Ferrero, R.
Some results on Ca, Mg, C and Si abundances are given for some A stars of the solar neighbourhood. The abundances are determined via the comparison of computed and observed line resonance profiles, in the framework of the NLTE theory, with atom models reduced to a few atomic levels. The obtained NLTE abundance values are then compared to the LTE o…