N. Bade

Simultaneous optical/gamma-ray observations of GRBs

We report on the on-going project to search for serendipitous time-correlated optical photographic observations of γ-ray bursts (GRBs). The regular photography at 12 observatories is used to look for plates which have been exposed simultaneously with a GRB detected by BATSE and contain its position. The results of this search for GRBs detected during the previous 4 yrs of BATSE operation are presented.

Rapid follow-up ROSAT observation of GRB 940301

The strong gamma-ray burst of March 1, 1994 was imaged by COMPTEL and found to have an identical location within the errors as a burst which occurred on July 4, 1993. This location coincidence had prompted speculations on a possible single source for both bursts. We have performed a ROSAT PSPC mosaic observation within four weeks of GRB 940301. The results of these observations and the comparison of the intensities of the detected sources with those detected during the ROSAT all-sky-survey in September 1990 will be presented. We conclude that a quiescent luminous X-ray source similar to the Soft Gamma Repeaters SGR 1806 20 and SGR 0525 66 is very unlikely.

The Hamburg Identification Program of Rosat All-Sky Survey Sources

The ROSAT All Sky Survey (RASS), performed between July 1990 and February 1991, provided about 60,000 X-ray sources in a soft X-ray band (0.1–2.4keV) with a flux limit of approximately 5 × 10-13 ergs cm-2 s-1 for exposure times of 400sec (a typical value in low ecliptic latitudes). A wealth of information can be extracted from the RASS source content and many objects deserve (or have already deserved) extensive follow-up studies. However, this possibility is limited by the fact that the nature of most of the RASS sources is unknown i.e., they are unclassified. A correlation with the SIMBAD data base yields only identifications for about one third of the RASS sources.

Simultaneous Optical/Gamma-ray Observations of GRBs

This status report presents details on the project to search for serendipitous time-correlated optical photographic observations of γ-ray bursters. The ongoing photographic observations at nine observatories are used to look for plates which have been exposed simultaneously with a γ-ray burst detected by BATSE and contain the burst position. The results for the third year of BATSE operation are presented.