Distribution and Variability of Cosmic X-Ray Sources

At least 30 discrete cosmic x-ray sources have been detected thus far. The distribution is concentrated toward the galactic plane, and most of the sources are believed to lie within 2 kiloparsecs of the sun. It is estimated that the average luminosity of the observed sources is about 5 x 10(36) ergs per second and that the entire galaxy contains about 1250 such sources. Comparisons of fluxes observed over the course of the past 2 years reveal that many sources are highly variable.