A Search for Nontriggered Gamma-Ray Bursts in the BATSE Continuous Records: First Results

An off-line scan for nontriggered gamma-ray bursts (GRBs) in the BATSE daily records at 1024 ms time resolution covering about 7 yr of observations gave 1353 nontriggered and 1581 triggered GRBs. The scan efficiency was measured by adding artificial test bursts to the data. The log N - log P distribution could be extended down to peak fluxes, P ~ 0.1 photons cm -2 s -1 . Previous indications of a turnover at small P are not confirmed. The log N - log P distribution cannot be fitted with a standard candle model with a nonevolving GRB source population, assuming that there are no large non-GRB contaminations. It is likely that the intrinsic luminosity function of GRBs is wide.