GAMMA-RAY ASTRONOMY - EXTENSION BEYOND THE GEV DOMAIN BY GROUND-BASEDOBSERVATIONS

Gamma-Ray Astronomy, originated with the OSO-3, SAS-2 and COS-B satell ites, has been renewed during the last three years by Compton-GRO's di scovery of tens of Galactic and extra-galactic sources up to approxima te to 10 GeV. Also in the last three years, a ground-based observing t echnique has emerged for TeV gamma rays: the identification of gamma-i nduced air showers via their Cerenkov emission. Extrapolating this tec hnique down to the present limit of satellite observations has become a realistic goal, allowing fundamental questions to be tackled which w ould remain open until the individual spectra were extended.