Highlights from the COS-B mission

Abstract

The European Space Agency's high-energy (E>50 MeV) gamma-ray observatory COS-B was operational from August 1975 to April 1982 and in that time made 65 observations of about 1 month duration and with a field-of-view of approximately 0.4 sr each. The high counting statistics achieved over the total mission allowed, for the first time, a detailed study of 1) the Galactic diffuse large-scale gamma-ray emissivity, 2) the small-scale gamma-ray structures caused by point-like sources and molecular clouds, and 3) the spectral and temperal behaviour of the Crab and the Vela pulsars. COS-B discovered the first high-energy extragalactic gamma-ray source (3C273) and resolved for the first time the emission from some local cloud complexes, notably the Orion-Monoceros and the Ophiuchus cloud complexes. For the latter case, in the Ophiuchus/Upper-Scorpius region there is circumstantial evidence for gamma-ray emission from molecular gas that was photodissociated after the passage of a SN shell.