Search for optical flashes from gamma-ray bursters

Abstract Preliminary results of an investigation of the Ondřejov and Sonneberg plate collections for possible optical counterparts to gamma ray bursters (GRBs) are presented. The study proceeds in 3 directions: as time-correlated searches for GRBs with known positions, as time-correlated searches for GRBs without known positions, and as archival searches. 3 GRBs with known positions and 28 GRBs without known positions were studied this way. Archival searches representing an exposure time of 2.75 years were done for 10 GRBs positions with limiting magnitudes for a 1 sec. flash between 3 and 8. The position of the Perseus flasher was also investigated using 1000 hours of monitoring. No evidence for true optical images associated with GRBs was found. Statistical conclusions are drawn and discussed.