(10ms). It is likely that both samples contain shorter time scales that cannot be resolved.

The counts variations within the pulses observed in the high resolution long bursts is high. In 41 out of 46 pulses, the photon counts drops to less than half of the maximal counts of the pulse on both sides. Therefore, like in short bursts, the statistically significant variations in the bursts reflects also a significant variation in the output of the source.

Walker, Schaefer & Fenimore (2000) performed a similar analysis of TTE data of 14 long bursts. They found only one long burst with very short time scales. The difference between the results arises from the different samples considered. Walker et al. (2000) considered the bursts with maximal total photon counts within the TTE burst record. We demanded that the counts will return close to the background level within the TTE record. Walker et al. (2000) criterion favors bursts that are active during the whole TTE record and therefore most of the bursts in their sample are dominated by a long and bright pulse.

This similarity between the short bursts and the fraction of long bursts raises the question whether it is possible that 