2002MNRAS.330..920N

We analyse a sample of bright short bursts from the BATSE 4B-catalog and find that many short bursts are highly variable (δt_min/T{Lt}1, where δt_min is the shortest pulse duration and T is the burst duration). This indicates that it is unlikely that short bursts are produced by external shocks. We also analyse the available (first 1-2s) high-resolution Time Tagged Events (TTE) data of some of the long bursts. We find that variability on a 10-ms time-scale is common in long bursts. This result shows that some long bursts are even more variable than it was thought before (δt_min/T~10^–4-10^–3).