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GCN Circular 18429

GRB 151021A: Swift-BAT refined analysis
2015-10-21T11:43:31Z (9 years ago)
Scott Barthelmy at NASA/GSFC <>
H. A. Krimm (GSFC/USRA), S. D. Barthelmy (GSFC), J. R. Cummings (GSFC/UMBC),
N. Gehrels (GSFC), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC),
A. Melandri (INAF-OAB), D. M. Palmer (LANL), T. Sakamoto (AGU),
M. Stamatikos (OSU), T. N. Ukwatta (LANL)
(i.e. the Swift-BAT team):
Using the data set from T-240 to T+352 sec from the recent telemetry downlinks,
we report further analysis of BAT GRB 151021A (trigger #660671)
(Melandri, et al., GCN Circ. 18425).  The BAT ground-calculated position is
RA, Dec = 337.647, -33.189 deg, which is 
   RA(J2000)  =  22h 30m 35.3s 
   Dec(J2000) = -33d 11' 21.8" 
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 10%.
The mask-weighted light curve shows many overlapping peaks starting
at ~T-50sec, with a maxiximum peak at ~T+1 sec, and ending at ~T+130 sec.
T90 (15-350 keV) is 110.2 +- 3.7 sec (estimated error including systematics).
The time-averaged spectrum from T-21.6 to T+127.4 sec (with a 1.5 sec data gap
in the middle) is best fit by a simple power-law model.  The power law index
of the time-averaged spectrum is 1.57 +- 0.04.  The fluence in the 15-150 keV band
is 2.8 +- 0.1 x 10^-5 erg/cm2.  The 1-sec peak photon flux measured from T-0.13 sec
in the 15-150 keV band is 9.7 +- 0.8 ph/cm2/sec.  All the quoted errors are
at the 90% confidence level. 
The results of the batgrbproduct analysis are available at
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