POSSIBLE EGRET GAMMA-RAY BURST DETECTION INDEPENDENT OF BATSE TRIGGERING

摘要

EGRET spark chamber data collected between 1991 April 22 and 1994 August 29 have, been analyzed for gamma-ray burst events independent of BATSE triggering. To date, five gamma-ray bursts that are coincident with a trigger from the BATSE instrument have been detected in the EGRET spark chamber. The EGRET-detected bursts have high-energy power-law tails and, in some cases, long duration emission. Because BATSE is sensitive in a lower energy range (25-600 keV), there may be other high energy gamma-ray bursts detectable with EGRET (30 MeV-30 GeV) that do not trigger BATSE. Also, bursts with long-duration emission may be more easily detected with EGRET. Furthermore, burst events may have occurred while BATSE was temporarily inactive. Two previously detected gamma-ray bursts were independently detected, and one new possible detection was made on a timescale of 3 minutes, although the significance is subject to systematic errors.