Low-energy gamma-ray sources observed by the MISO telescope

Observations of several galactic and extragalactic sources by the MISO telescope, a gamma-ray detector operating in the (0.1-20) MeV energy range, are examined. The observations discussed are those of the Crab Nebula, Cygnus X-1, COS-B high-energy (more than 50 MeV) gamma-ray sources, the Seyfert galaxies NGC 4151 and MCG 8-11-11, the 'peculiar' galaxy NGC 1275, and the BL LAC object MK 501. The data on NGC 4151 and MCG 8-11-11 are consistent with power-law spectra having proton indices alpha approximately equal to unity in the (0.1-3) MeV range. Above this energy, MISO and SAS-2/COS-B measurements require spectral breaks to alpha approximately equal to or greater than 3. Upper limits are obtained on the emission from both MK 501 and NGC 1275.