REAL-TIME OPTICAL FLUX LIMITS FROM GAMMA-RAY BURSTS MEASURED BY THE GAMMA-RAY OPTICAL COUNTERPART SEARCH EXPERIMENT

The Gamma-Ray Optical Counterpart Search Experiment presents new exper imental upper limits on the optical flux from gamma-ray bursts (GRBs). Our experiment consisted of a fully automated very wide-held opto-ele ctronic detection system that imaged locations of GRBs within a few se conds of receiving trigger signals provided by BATSE's real-time burst coordinate distribution network. The experiment acquired 3800 observi ng hours, recording 22 gamma-ray burst triggers within similar to 30 s of the start of the burst event. Some of these bursts were imaged whi le gamma-ray radiation was being detected by BATSE. We identified no o ptical counterparts associated with gamma-ray bursts among these event s at the m(V) similar to 7.0-8.3 sensitivity level. We find the ratio of the upper limit to the V-band optical flux, F-nu, to the gamma-ray fluence, Phi(gamma), from these data to be 1 x 10(-18) < F-nu/Phi(gamm a) < 2 x 10(-16).