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GCN Circular 6429

Subject
GRB 070520B, Swift-BAT refined analysis
Date
2007-05-21T00:15:51Z (17 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@lheamail.gsfc.nasa.gov>
T. Sakamoto (GSFC/ORAU), L. Barbier (GSFC), S. D. Barthelmy (GSFC),
J. Cummings (GSFC/UMBC), E. Fenimore (LANL), N. Gehrels (GSFC),
H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), A. Moretti (INAF-OAB),
D. Palmer (LANL), A. Parsons (GSFC), G. Sato (GSFC/ISAS),
M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC)
on behalf of the Swift-BAT team:
 
Using the data set from T-239 to T+592 sec from recent telemetry downlinks,
we report further analysis of BAT GRB 070520B (trigger #279898)
(Moretti, et al., GCN Circ. 6245).  The BAT ground-calculated position is
RA, Dec = 121.886, 57.588 deg  which is 
   RA(J2000)  = 08h 07m 32.7s 
   Dec(J2000) = 57d 35' 15.3" 
with an uncertainty of 1.8 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 59%.
 
The mask-weighted light curve shows two overlapping peaks starting
at T-4 sec, peaking at T+1 sec, and ending with a long tail at T+200 sec.
T90 (15-350 keV) is 66 +- 4 sec (estimated error including systematics).
 
The time-averaged spectrum from T-5.0 to T+71.3 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.15 +- 0.21.  The fluence in the 15-150 keV band is 9.2 +- 1.1 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T+0.74 sec in the 15-150 keV band
is 0.4 +- 0.1 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level.
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