GCN Circular 154

T. Giblin & P. Woods (University of Alabama in Huntsville and NASA 
Marshall Space Flight Center) report on behalf of the BATSE GRB team:

On September 23.8408 (UT) BATSE detected an extraordinary GRB 
(GRB 980923 - BATSE Trigger 7113). The event consists of an episode 
of rapid variability lasting from the trigger time to approximately 
38 seconds, followed by a smooth emission tail out to ~100 seconds. 
The rapid variability is comprised of a series of HE (high-energy) 
pulses in rapid succession whose peak intensities, on average, 
increase with time, unlike the temporal decay of intensity typically 
found in most bursts. The emission tail lacks HE emission and is 
approximately 3% of the burst peak intensity (in the 25-2000 keV range). 

A peak flux (integrated over 0.064 seconds) in the 50-300 keV range 
of 54.0 +/- 0.8 photons s^-1 cm^-2 places it in the top 0.5% of the 
BATSE peak flux distribution. The fluence above 25 keV is 4.84 +/- 0.02
x 10^-4, ranking 3rd among all BATSE GRBs. Only GRB 940703 (trigger 3057) 
and GRB 940217 (trigger 2831) have a higher fluence (> 25 keV) than GRB 
980923. The location and basic information for this burst as well as the 
latest 20 BATSE GRBs can be retrieved at

http://www.batse.msfc.nasa.gov/data/grb/catalog/basic_latest.html

A lightcurve is available at 

http://www.batse.msfc.nasa.gov/~kippen/batserbr/ 


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