The average temporal profile of BATSE gamma‐ray bursts: Comparison between strong and weak events

First results are presented from the analysis of 260 BATSE gamma‐ray bursts (GRBs) using a method whereby all events are synchronized and averaged around the bins which are the brightest time intervals of each of them. For the averaged time history, a difference is found between the rise front and the back slope, and good evidence is found for the presence of hard‐to‐soft spectral evolution. We compare sub‐sets of ‘‘strong’’ and ‘‘weak’’ events and find no evidence for time dilation in weak GRBs, as would be expected in cosmological GRB models. On the other hand, for the strong events the averaged hardness ratio is found to be larger than for the weak GRBs.