1995A&A...296L..41H

One observational consequence of a cosmological distribution of γ-ray bursts is that some recurrent bursts, due to gravitational lensing, should be seen during the life time of the Compton Gamma-Ray Observatory. These would be identifiable by their spatial coincidence and by their identical time profiles and spectra. The COMPTEL experiment, on board the Compton Gamma-Ray Observatory, has imaged two γ-ray bursts(GRB 930704 and GRB 940301) with coincident locations, separated in time by eight months. We report here on the spectral andtemporal analysis of these two events in order to establish whether they are gravitationally lensed images of the same burst. We conclude that although the envelopes of the time profiles are similar, they are sufficiently different on short time scales to rule out the standard lensing hypothesis. Furthermore, spectral dissimilarities between the pair mitigate against the possibility that the differences in time profiles could have arisen through microlensing. Since lensing is ruled out, the remaining possibilities are an accidental coincidence of unrelated bursts or a true repeating burst source. The latter would severely constrain cosmological burst models.