HIGH-ENERGY GAMMA-RAYS FROM THE SUN AS SEEN BY THE GAMMA-1 TELESCOPE

The gamma-ray telescope GAMMA-1 has been operated from July 11, 1990, to February 28, 1992. During this period, the Sun was observed as a primary target several times, when its activity was on an increasing phase. Four outstanding flares were recorded , with energy in the range 30 - 2000 MeV. Spectral analysis with the use of maximum likelihood and maximum entropy methods has revealed differences in gamma-ray production mechanisms. In the impulsive March 26, 1991 event high energy gamma-rays originate exclusively as a bremstrahlung of primary accelerated electrons. In contrast , the gamma ray emission of the extended phase of June 15, 1991 flare is mainly due to the decay of neutral pions. The average spectral index for primary nucleons was - 3.6. Evolution of the spectra for both flares shows tendency to a decrease of the primary particles mean energies with time. The third and fourth flares were recorded. on October 15 and 16, 1991, but the poor quality of the telemetry has delayed the data analysis