Prognoz 2 was launched on 29 June 1972. It was put into
a highly elliptical orbit with apogee 200,000 km, perigee 550 km, and
inclination 65 degrees. It carried the first instrument package, SIGNE 1,
resulting from the Franco-Soviet SIGNE collaboration. This instrument was
intended to perform solar radiation studies. However, it detected cosmic
gamma-ray bursts as well as solar events.
Prognoz 2 reentered the atmosphere on 15 December 1982.
The SIGNE 1 detector consisted of a Stilbene scintillator, 38.1 mm in
diameter and 38.1 mm high. It was shielded by a plastic anticoincidence
scintillator. There were 8 energy channels: 0.4-0.7 MeV, 0.7-1.0 MeV, 1-1.6
MeV, 1.6-2.4 MeV, 2.4-2.9 MeV, 2.9-3.9 MeV, 3.9-8.1 MeV, and 8.1-11.8 MeV.
Counts were integrated for every 41 or 160 seconds, depending on the experiment
mode. The effective area was 17.1 cm2.