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GCN Circular 3145

Subject
GRB 050326 BAT refined analysis
Date
2005-03-26T15:43:26Z (19 years ago)
From
Jay R. Cummings at NASA/GSFC/Swift <jayc@milkyway.gsfc.nasa.gov>
J. Cummings (GSFC/NRC), S. Barthelmy, L. Barbier (GSFC),
E. Fenimore (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. Tashiro (Saitama U.), J. Tueller (GSFC),
N. White (GSFC)
on behalf of the Swift/BAT team:

At 09:53:55 UT Swift-BAT detected GRB 050326 (Markwardt et al. 
GCN Circ 3143). The refined BAT ground position is (RA,Dec) = 
6.892, -71.376 [deg; J2000] +- 3 arcmin, (95% containment).

The burst had 6 distinct peaks, with several smaller peaks. There
was an initial weak peak (at T-9) followed by a 10 times
larger peak, which caused the trigger (defined as 0 seconds). 
Major peaks were at +5, +9, +19, and +23 seconds, all of similar 
spectral shape.

The fluence derived from the event data was 1.9 X 10^-5 erg/cm^2
in the 15-350 keV band.  The 1-s peak flux was 17 ph/cm^2/s
(also 15-350 keV).  The photon index of the 1-s peak spectrum
(T+0 s) was 0.98 +/- 0.05 (90% confidence).  The time-averaged
spectrum yields a photon index of 1.28 +/- 0.03 (90% confidence). 
The overall measure of burst duration was T90 = 29.5 +/- 2 s
(including systematics) T50 was 19 seconds.

Clarification on recent BAT triggers and notices:
This was BAT trigger number 112453, for which no real-time notices
were sent. It was NOT trigger 112467, a provisional trigger,
for which real-time notices WERE sent.

[GCN OPS NOTE (28mar05):  Per author's request, the trigger number
was changed from ''111453' to '112453'.]
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