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Photometric and spectroscopic studies of cool stars discovered in EXOSAT X-ray images. III. Photometric properties.

Tagliaferri, G.; Pasquini, L.; Pallavicini, R. +2 more

We present high-precision UBV(RI)_c_ photometry for a sample of active stars detected serendipitously by the EXOSAT satellite. Fourteen objects, out of 47 likely optical counterparts, turned out to be clearly variable, with periods in the range 1-8 days, including a newly discovered eclipsing binary. For most of them the optical variability is con…

The canonical X-ray/gamma-ray spectrum of Seyfert 1s and low-state Galactic black hole candidates.

Zdziarski, A. A.; Magdziarz, P.; Gierlinski, M. +1 more

We review broad-band X-ray/γ-ray spectra of radio-quiet Seyfert 1s as well as of Galactic black hole candidates in the low state. The spectra share their basic components: an underlying power law, a Compton-reflection component with an Fe Kα line, low-energy absorption by cold matter, and a high-energy cutoff above ~200keV. The X-ray energy spectr…

X-ray map from the EXOSAT galactic plane survey and a direct demodulation technique.

Lu, F. J.; Li, T. P.; Page, C. G. +2 more

In 1984 the EXOSAT observatory scanned the galactic plane with its medium-energy array which had a spatial resolution of about 0.75deg. The data analysis used at that time was unable to resolve some of the more complex regions near the galactic centre. The direct demodulation method is a technique to solve the image reconstruction problem in high …