Cos-B

Cos-B
	Cos-B, a satellite to study cosmic gamma-rays
Mission type	Astronomy
Operator	ESA
COSPAR ID	1975-072A
SATCAT no.	08062
Mission duration	2.5 years (planned); 10 years, 5 months and 8 days (achieved)
Start of mission
Launch date	9 August 1975, 01:48:00 UTC
Rocket	Delta 2913
Launch site	Vandenberg Air Force Base, SLC-2W
End of mission
Decay date	18 January 1986
Orbital parameters
Reference system	Geocentric orbit
Regime	Low Earth orbit

COS-B (Celestial Observation Satellite B) ^[1] was the first European Space Research Organisation (ESRO) mission to study cosmic gamma ray sources. COS-B was first put forward by the European scientific community in the mid-1960s and approved by the ESRO council in 1969. The mission consisted of a satellite containing gamma-ray detectors, which was launched by NASA on behalf of the ESRO on 9 August 1975. The mission was completed on 25 April 1982, after the satellite had been operational for more than 6.5 years, four years longer than planned and had increased the amount of data on gamma rays by a factor of 25. Scientific results included the 2CG Catalogue listing around 25 gamma ray sources and a map of the Milky Way. The satellite also observed the X-ray binary Cygnus X-3.