The Astrophysical Journal
The American Astronomical Society
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 j error circle and the interplanetary network annulus. No optical transients were observed brighter than the m » 11 completeness limit of the resulting images, providing a new V upper limit on the ratio of simultaneous optical to gamma-ray fluence of R < 1024 and on the ratio of L simultaneous optical (at 700 nm) to gamma-ray (at 100 keV) flux density of R ! 305 for a B-type spectrum and R < 475 for an M-type spectrum.
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