Optical Flashes Preceding GRBs

Abstract

Only one optical flash associated with a gamma-ray burst has been detected so far by ROTSE. There are also upper limits obtained by several groups for several bursts. Recent model calculations indicate a possibility that optical flash may precede the main GRB. Such flashes are undetectable in the currently popular observing mode, with optical instruments responding to GRB triggers. There is a need to develop all sky optical monitoring system capable of recognizing flashes in real time, and more powerful instruments that could respond robotically to optical triggers and carry out follow up observations.