New results on the time histories of gamma-ray bursts

A study of the morphology of 14 short ( 1 s) gamma ray bursts observed by the Franco Soviet SIGNE detectors onboard the VENERA spacecraft between 1978 and 1982 is presented. We find two major groups of short bursts characterised not only by their different durations ( 1 s and 100 ms respectively), but also by different e-folding rise and decay times. A study of the time history of the impulsive portion of the 1979 March 5 event at 2 ms resolution shows evidence for a previously undiscovered 23ms quasi periodicity. These results are discussed in the context of neutron star models for gamma ray bursters.