2.2. Temporal Structure and Variability
The bursts have a complicated and irregular time profiles which vary
drastically from one burst to another. Several time profiles,
selected from the second BATSE catalog, are shown in
Fig. 1. In most bursts, the typical variation
takes place on a time-scale
T significantly
smaller than the total duration
of the burst, T. In a minority of the bursts there is only one peak
with no substructure and in this case
T ~ T. It
turns out
that the observed variability provides an interesting clue to the
nature of GRBs. We discuss this in section 7. We
define the ratio
T /
T which is a
measure of the
variability. Fig. 2 depicts the total observed
counts (at E > 25 keV) from GRB1676. The bursts lasted
T ~ 100 sec and it had peaks of width
T ~ 1 sec,
leading to
= 100.
![]() |
Figure 1. Total number of counts vs. time for several bursts from the BATSE Catalogue. Note the large diversity of temporal structure observed. |
![]() |
Figure 2. Counts vs. time for BATSE burst
1676. The bursts lasted T ~ 60 sec and it had peaks of width
|