* Astronomy

Cosmos 428 was launched by the USSR into Earth orbit on June 24, 1971 and recovered July 6, 1971. The orbit characteristics: apogee/perigee/inclination 208 km, 271 km, and 51.8°, respectively. It was a military satellite on which X-ray astronomy experiments had been added. There was a scintillation spectrometer sensitive to X-rays >30 keV, with a 2° × 17° field of view. In addition, there was an X-ray telescope which operated in the range 2-30 keV. Cosmos 428 detected several X-ray sources which were correlated to already identified Uhuru point sources.
Source