POSSIBLE EGRET GAMMA-RAY BURST DETECTION INDEPENDENT OF BATSE TRIGGERING

EGRET spark chamber data collected between 1991 April 22 and 1994 Augu st 29 have been analyzed for gamma-ray burst events independent of BAT SE triggering. To date, five gamma-ray bursts that are coincident with a trigger from the BATSE instrument have been detected in the EGRET s park chamber. The EGRET-detected bursts have high-energy power-law tai ls and, in some cases, long duration emission. Because BATSE is sensit ive in a lower energy range (25-600 keV), there may be other high ener gy gamma-ray bursts detectable with EGRET (30 MeV-30 GeV) that do not trigger BATSE. Also, bursts with long-duration emission may be more ea sily detected with EGRET. Furthermore, burst events may have occurred while BATSE was temporarily inactive. Two previously detected gamma-ra y bursts were independently detected, and one new possible detection w as made on a timescale of 3 minutes, although the significance is subj ect to systematic errors.