The spin-X wide-field X-ray monitor of the spectrum-X-gamma astrophysical observatory

The Spin-X wide-held X-lay monitor of the Spectrum-X-Gamma astrophysical ob servatory, which is based on the principle of a coded-aperture telescope, i s designed to detect and localize cosmic gamma-ray-burst (GRB) sources; to survey large areas of the sky in search of new transients; and to carry out long-term observations of blight Galactic soul ces: including X-ray burste rs. The monitor consists of two noncoaxial identical modules, Spin-X1 and S pin-X2, which together cover 6.8% of the sky. The high-apogee, four-day orb it of the Spectrum-XG satellite allows the instrument to be in observing mo de more than 50% of the time. Having simulated the rate of GRB detection by Spin-X, we show that extrapolating BATSE 50-300-keV average data on the nu mber of GRBs, their duration, and their mean energy spectrum to the X-ray e nergy band leads to disagreement with the observed detection rate of GRBs i n the X-ray band. The number of GRBs that can be detected and localized wit h an accuracy r less than or equal to 3' (3 sigma) (the error-circle radius ) by Spin-X is estimated to be ten bursts per year. We present data on the Spin-X sensitivity achievable during long-term observations of persistent a nd transient sources and on its sensitivity to X-ray bursts from Galactic s ources in the 2-30-keV energy band. (C) 2000 MAIK "Nauka/Interperiodica".