Observations of intense cosmic X-ray bursts.

Nine cosmic X-ray bursts with energy fluxes greater than 40 billionths erg per sq cm per sec that were observed by Vela satellite detectors in the 15 month period from May 1969 to August 1970 are described. Their distribution indicates that the sources are galactic with peak luminosities of 10 to the 37th to 10 to the 38th power erg per sec in the 3-12 keV energy range and that the bursts occur a few thousand times per year. The assumption of a common energy spectrum for the X-ray bursts and the cosmic gamma-ray bursts leads to a consistent prediction of the rate of occurrence of the brief transients.