Characteristics of cosmic X-ray bursts observed with the OGO-5 satellite.

Observations of 11 cosmic X-ray bursts made with the solar X-ray spectrometer aboard OGO 5 are presented. Their identification as cosmic events is based on good time coincidence with observations of cosmic gamma-ray bursts reported in the literature. The OGO-5 experiment is most sensitive to cosmic X-ray sources located in the sunward hemisphere. When this condition was satisfied and the OGO-5 experiment was operating normally, almost every cosmic gamma-ray burst reported by other observers was detected at X-ray energies of at least 32 keV. In three events the spectrum was observed down to about 10 keV. Two intense events were observed with 0.288-s time resolution, and large time variations were observed to occur in times not exceeding 0.3 s. Evidence is found that most cosmic gamma-ray bursts have photon spectra extending down to about 10 keV. The origin of these cosmic events in processes similar to those believed to occur in solar flares is briefly examined.