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Type: Research satellite
Operator: European space agencyESA ESA
COSPAR-ID : 1975-072A
Mission dates
Dimensions: 277.5 kg
Begin: August 9, 1975, 01:48 UTC
Starting place: Vandenberg AFB , SLC-2W
Launcher: Delta 2913
Status: in orbit, out of order
Orbit data
Rotation time : 37 h
Orbit inclination : 90.13 °
Apogee height 99876 km
Perigee height 340 km
Eccentricity : 0.880997

COS-B (Cosmic Ray Satellite B) was a scientific satellite of the European Space Agency (ESA) for the study of cosmic gamma rays .

COS-B was on August 9, 1975 a Delta rocket of NASA from the launch site Vandenberg placed in a highly eccentric orbit with 37 hours turnaround time, and had until April 25, 1982 in operation. The main instrument was a large, direction-resolving detector ( spark chamber ) for gamma radiation between about 30 MeV and 5 GeV energy, and there was also a detector for X-rays. COS-B was an ESA project with contributions from European research institutes on instrumentation.

The first map of the gamma radiation of our Milky Way , the 2CG catalog of 25 cosmic gamma sources, and investigations of individual objects such as pulsars and the first extragalactic gamma source 3C 273 emerged from the observations of COS-B .


  1. ESA SP 1235: A history of the European Space Agency 1958–1987 , page 14 (PDF; 3.2 MB)

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