Real-Time Optical Flux Limits From Gamma-Ray Bursts Measured By The GROCSE Experiment

The Gamma-Ray Optical Counterpart Search Experiment (GROCSE) presents new experimental upper limits on the optical flux from gamma-ray bursts (GRBs). Our experiment consisted of a fully-automated very wide-field opto-electronic detection system that imaged locations of GRBs within a few seconds of receiving trigger signals provided by BATSE’s real-time burst coordinate distribution network (BACODINE). The experiment acquired 3800 observing hours, recording 22 gamma-ray burst triggers within ∼30 s of the start of the burst event. Some of these bursts were imaged while gamma-ray radiation was being detected by BATSE. We identified no optical counterparts associated with gamma-ray bursts amongst these events at the mV ∼ 7.0 to 8.5 sensitivity level. We find the ratio of the upper limit to the V-band optical flux, Fν , to the gamma-ray fluence, Φγ, from these data to be 2× 10 −18 < Fν/Φγ < 2× 10 . Subject headings: gamma rays: bursts