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/ This message is citeable.