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GCN Circular 463

GRB 991216: Extremely bright BATSE burst
1999-12-16T23:40:52Z (24 years ago)
R. Marc Kippen at BATSE/UAH/MSFC <>
R. M. Kippen, R. D. Preece and T. Giblin (University of Alabama in
Huntsville) report on behalf of the BATSE GRB team:

An extremely bright gamma-ray burst was detected by BATSE on 1999
December 16.671544 UT (trigger number 7906).  The event began with a
weak precursor pulse lasting about 3 seconds, followed about 15
seconds later by an intense multi-peaked complex.  The main emission
lasted about 20 seconds, but a long decay tail persisted for another
30 seconds.  Using preliminary rapid burst response data (not
corrected for deadtime), we estimate that the peak flux was >60
photons cmE-2 sE-1 (50-300 keV; integrated over 1.024 s), and the
total fluence was >2 x 10E-4 erg cmE-2 (>20 keV).  This burst is thus
one of the brightest (if not the brightest) ever detected by BATSE.
The spectral properties appear to be typical of other GRBs.

The BATSE rapid burst response location of this event is (Ra, Dec
J2000) = (79.81, 10.79) degrees, with a total uncertainty radius of
2.4 deg (68% conf.).  Given that more precise localizations from
RXTE-PCA and IPN and probable, we strongly encourage observations by
wide-field telescopes.  A location sky-map and lightcurve for this
event are available at

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