New Constraints on Simultaneous Optical Emission From Gamma-Ray Bursts Measured by the Livermore Optical Transient Imaging System Experiment

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Abstract
LOTIS is a gamma-ray burst optical counterpart search experiment located near Lawrence Livermore National Laboratory in California. Since operations began in 1996 October, LOTIS has responded to five triggers as of 1997 July 30, which occurred during good weather conditions. GRB 970223 (BATSE trigger 6100) was an exceptionally strong burst, lasting ~30 s with a peak at ~8 s. LOTIS began imaging the error box ~11 s after the burst began and achieved simultaneous optical coverage of 100% of the region enclosed by the BATSE 3 σ error circle and the interplanetary network annulus. No optical transients were observed brighter than the mV~11 completeness limit of the resulting images, providing a new upper limit on the ratio of simultaneous optical to gamma-ray fluence of RL−4 and on the ratio of simultaneous optical (at 700 nm) to gamma-ray (at 100 keV) flux density of RFRF<475 for an M-type spectrum.