The low energy emission of Gamma Ray Bursts (GRBs) has been confirmed by recent detections of Optical Afterglows (OA) of GRBs observed by BeppoSAX. The optical detections of GRBs starts at 3 hrs after the GRB occurrence in the best case. This is roughly the technical limit of BeppoSAX GRB detection and distribution method: no information can be sent to ground based observers prior this limit. This means that no deeper optical data (mag 12 or better) are available for GRBs for times before and during the gamma ray events as well as immediately (less than 3 hrs) after for precisely positioned BeppoSAX triggers. The above mentioned technical limit also means that for these triggers, the real-time optical data can be provided only by sky patrol experiments.
Two such patrols are operated in the world, namely the variable star patrol at the Sonneberg Observatory and the meteor patrol at the Ondrejov Observatory. Here we report on the preliminary results of the investigation of Sonneberg and Ondrejov sky patrol plates for GRBs including the precisely positioned GRBs (by CGRO Comptel and by BeppoSAX) and discuss the importance of such real-time and pre-burst optical data for GRBs.
Copyright The European Southern Observatory (ESO)