We study the temporal asymmetry of over 600 bursts from the BATSE 3B catalog , encompassing a 200-fold range in peak flux .
By comparing the rates of rise and fall of the flux near the highest burst peak , we find that about two-thirds of the bursts exhibit a preferred asymmetry in the sense that the flux rises more rapidly than it falls , confirming the conclusions of previous studies employing smaller databases .
The statistical significance of the average time asymmetry of the sample is > 99.999 % ; therefore , models that predict time symmetry of the burst profile are ruled out .
We find no statistically significant correlation between burst temporal asymmetry and peak .
This result is consistent with both cosmological and local interpretations of the gamma ray burst phenomenon .