Observation of gamma ray bursts and flares by the EGRET telescope on the Compton Gamma Ray observatory

E J Schneid,R Hartman,J R Mattox,P L Nolan,D J Thompson,S D Hunter,M A Mayer-Hasselwander,P Sreekumar,G Kanbach,K Pinkau,D L Bertsch,P F Michelson,M Sommer,C E Fichtel,D A Kniffen,Y C Lin,P W Kwok,C Von Montigny,H Rothermel

doi:10.1063/1.42768

Abstract

The Energetic Gamma Ray Experiment Telescope (EGRET) on the Compton Gamma Ray observatory has observed energetic gamma ray bursts and flares. On May 3, 1991, EGRET detected a gamma ray burst both in the energy measuring NaI (Tl) scintillator and independently in the spark chamber imaging assembly. The NaI spectra were accumulated by a special BURST mode of EGRET. The spectra were measured over a range from 1 to 200 MeV, in three sequential spectra of 1, 2, and 4 seconds. During the peak of the burst, six individual gamma rays were detected in the spark chamber, allowing a determination of the burst arrival direction. The intense flares of June were also detected. A solar flare on June 4 was observed to last for several minutes and for a brief time, less than a minute, had significant emission of gamma rays exceeding 150 MeV.

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