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GCN Circular 4864

GRB 060312: Refined analysis of the Swift-BAT burst
2006-03-12T17:09:19Z (18 years ago)
Scott Barthelmy at NASA/GSFC <>
H. Krimm (GSFC/USRA), L. Barbier (GSFC), S. Barthelmy (GSFC),
J. Cummings (GSFC/NRC), E. Fenimore (LANL), N. Gehrels (GSFC),
D. Grupe (PSU), D. Hullinger (BYU-Idaho), C. Markwardt (GSFC/UMD), 
D. Palmer (LANL), A. Parsons (GSFC), T. Sakamoto (GSFC/NRC),
G. Sato (ISAS), J. Tueller (GSFC)
on behalf of the Swift-BAT team:

Using the data set from T-300 to T+302 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 060312 (trigger #201391)
(Grupe, et al., GCN 4859).  The BAT ground-calculated position is RA,Dec =
45.777,+12.825 deg {3h 3m 6.5s,+12d 49' 29.6"} (J2000) +- 0.9 arcmin,
(radius, sys+stat, 90% containment).  The partial coding was 100%.
The mask-weighted lightcurve shows two main peaks at T-27 and T+7 sec.
The first peak starts at T-35 sec and the second ends at ~T+30 sec.
T90 (15-350 keV) is 43 +- 3 sec (estimated error including systematics).
The time-averaged spectrum from T-29.4 to T+22.0 is best fit by a power law
with an exponential cutoff.  This fit gives a photon index 1.35 +- 0.34, 
and Epeak of 62.8 +- 21.5 keV (chi squared 46.33 for 56 d.o.f.).  
For this model the total fluence in the 15-150 keV band is
1.8 +- 0.1 x 10^-06 erg/cm2 and the 1-sec peak flux measured from
T+5.63 sec in the 15-150 keV band is 1.5 +- 0.1 ph/cm2/sec.  
A fit to a simple power law gives a photon index of 1.85 +- 0.08
(chi squared 52.99 for 57 d.o.f.).  All the quoted errors are at the 90%
confidence level.
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