The COS-B experiment and mission

The COS-B satellite carries a single spark-chamber experiment capable of detecting gamma rays with energies greater than 30 MeV. The mission objectives are to study the spatial, energy and time characteristics of high-energy radiation of galactic and extragalactic origin. Correlation of X-ray and gamma-ray variations is obtained by the inclusion in the payload of a proportional counter sensitive to X-rays of 2 to 12 keV. The satellite was launched in August 1975 into an eccentric polar orbit, chosen to optimise the observability of interesting regions of the sky and the recovery of data. An important feature of the COS-B operations is a facility for the preliminary, but complete, analysis of a significant fraction of acquired data within a day or two of acquisition. This provides a means of alerting the experimenters to potentially interesting results well in advance of the availability of the complete data. The in-orbit performance of the experiment is shown to be consistent with the predictions of pre-launch calibrations made with particle accelerators