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GCN Circular 3219

Swift-BAT detection of GRB 050410
2005-04-10T16:00:04Z (19 years ago)
Scott Barthelmy at NASA/GSFC <>
E. Fenimore (LANL), L. Barbier, S. Barthelmy (GSFC), J. Cummings (GSFC/NRC),
M. Galassi (LANL), N. Gehrels (GSFC), D. Hullinger (UMD), H. Krimm (GSFC/USRA),
C. Markwardt (GSFC/UMD), D. Palmer (LANL), A. Parsons (GSFC),
T. Sakamoto (GSFC/NRC), G. Sato (ISAS), M. Suzuki (Saitama),
M. Tripicco (GSFC-SSAI), J. Tueller (GSFC)
on behalf of the Swift-BAT team:

At 12:14:25.36 UT Swift-BAT triggered on burst GRB 050410 (trigger=114298).
The BAT ground position is RA,Dec=89.745,+79.601 (J2000).  We note this
is 38 arcsec from the XRT position (Parola, et al, Circ 3218).  For this GRB
there were two BAT triggers (114298 and 114299; 9 sec apart).  This is a result
of a rare timing condition in the on-board software where the triggering code 
times-out while waiting for the imaging results of the first trigger,
then BAT goes back into the triggerable state, and then triggers again
(on the same burst) which then produces the second trigger number and
the second series of BAT-related GCN Notices.

The lightcurve shows a broad peak with a total burst duration of ~65 sec
(T90=43sec in 15-350 keV).  The rise of the burst was slow, causing a
delayed trigger, which continued to the back-to-back triggering situation.
The burst starts about 10 sec before the 114298 trigger time. 

A simple power law fit yields a photon index of -1.6 +/- 0.1, a burst fluence
of 6.9e-6 erg/cm2 , and the 1-sec peak flux of 2.0 ph/cm2/sec (15-350 keV).
There is emission across the full BAT range including the 100-350 keV band.
The burst was 43 deg off the BAT bore sight with a partial coding of 20%.
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