The X-ray and optical variability of the BLRG 3C390.3

We describe the optical emission line and continuum changes in 3C390.3. Also we present new EXOSAT results, and discuss their implication for determination of the X-ray spectrum — spectral index and absorbing column.     

EXOSAT spectra of some bright QSO's

This paper reports on EXOSAT observations of four bright QSO's and active galaxies. The QSO PHL 1657 has a simple spectrum that can be fit with power law plus some low energy absorption. A soft excess is observed for both MR 2251 and E 1352.24+1830. Finally, PKS 2126-158 was detected and the results are consistent with a 0.7 energy index.     

The brief history of experimental research of cosmic ray variations in Yakutia

Some unknown historical facts of cosmic ray studies in the north-east of the former Soviet Union related to the Yakutsk scientific group are reported for the benefit of the international scientific community. It focuses on the founders of Yu.G. Shafer Institute of Cosmophysical Research and Aeronomy of Siberian Branch of Russian Academy of Sciences. A chronology of measurements of cosmic ray intensity variations since 1949 in Yakutia (Sakha Republic; NE Siberia) is given. In particular, for the first time the data of the first solar cosmic ray event registered at Yakutsk (GLE04), with a small ionization chamber S-2 (volume: 20 L) are presented. Moreover, the data of the large ionization chamber ASK-1 (volume: 950 L) for the 1953–2003 period useful for specialists in the field of cosmic ray variations are also shown.     

The x-ray experiment on-board the “astron”

This paper describes the X-ray instrumentation, its capabilities and preliminary results which have been obtained for first two months operation.     

High and medium resolution spectroscopy of the X-ray transient 4U1543-47

Preliminary results of an EXOSAT observation of the transient X-ray source 4U1543-47 are presented. The source was observed in August 1983, during a high state, following a Tenma alert that the source was again active. Results from the GSPC and the LE 1000 l/mm grating are presented. The spectrum is complex, but in the 2–10 keV energy range can be well described by a Comptonised thermal distribution. Extrapolating the same model into the lower energy band of the grating requires an absorption column density equivalent to 2 × 10²¹ H cm². A marked under-abundance of Oxygen and overabundance of Nitrogen, along with a strong, unidentified line feature at 9.8 Å, are necessary to model the grating data.