EGRET OVERVIEW - ACHIEVEMENTS IN THE LIGHT OF EXPECTATIONS

The Energetic Gamma Ray Experiment Telescope (EGRET) on the Compton Ga mma Ray Observatory (CGRO) has over ten times the sensitivity of earli er high- energy gamma-ray telescopes flown in space. It covers the ene rgy range from about 3 10(7) eV to approximately 3 10(10) eV. As antic ipated, EGRET has indeed produced exciting and important new results o n a broad range of astrophysical topics. Highlights include: (1) the f inding of a new class of objects - high energy gamma-ray emitting blaz ars, (2) the emission of high energy gamma-rays from a gamma ray burst for over an hour, with some gamma rays having energies over a GeV and two having energies over 10 GeV, (3) the observation of seven high en ergy gamma ray pulsars, (4) the determination with high certainty that cosmic rays are galactic, (5) the detailed mapping of the galactic di ffuse radiation and the measurement of the pion bump in the high energ y gamma-ray energy spectrum, (6) the absence of microsecond bursts and its implication for certain physics unification theories, (7) the lon g trapping time of over ten hours for energetic solar particles follow ing a flare, and (8) a measurement of the extragalactic diffuse radiat ion and its consistency with that expected from AGN emission.