Hard X-ray emission from SN 1987A.

Hard X-ray emission from SN 1987A has been discovered by the HEXE and Pulsar X-1 instruments from the Mir-Kvant observatory "Röntgen" as well as from the X-ray astronomy satellite Ginga in August - September 1987. The detection of ⁵⁶Co decay lines by the gamma-ray-spectrometer on the SMM satellite and on balloon experiments as well as the decline time scale of the optical light curve and ⁵⁶Co lines observed in the infrared indicate that downscattered gamma radiation of the radioactive decay of ⁵⁶Co is the main source for the hard X-ray emission.