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GCN Circular 29632

Subject
GRB 210307A: Swift-BAT refined analysis
Date
2021-03-09T03:07:58Z (3 years ago)
From
Takanori Sakamoto at AGU <tsakamoto@phys.aoyama.ac.jp>
C. B. Markwardt (GSFC), E. Ambrosi (INAF-IASFPA), S. D. Barthelmy (GSFC),
J. R. Cummings (CPI), H. A. Krimm (NSF), S. Laha (GSFC/UMBC),
A. Y. Lien (GSFC/UMBC), 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-239 to T+700 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 210307A (trigger #1036139)
(Ambrosi, et al., GCN Circ. 29610).  The BAT ground-calculated position is
RA, Dec = 119.244, -66.965 deg which is
    RA(J2000)  =  07h 56m 58.5s
    Dec(J2000) = -66d 57' 54.3"
with an uncertainty of 2.1 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 79%.
  
The mask-weighted light curve shows two isolated peaks.  The initial peak starts
at T-30 sec, peaks at T0 and ends at T+40 sec.  The second peak starts at
T+110 sec, peaks at T+118 sec and ends at T+150 sec.  T90 (15-350 keV) is
262 +- 83 sec (estimated error including systematics).

The time-averaged spectrum from T-159.61 to T+174.53 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.56 +- 0.16.  The fluence in the 15-150 keV band is 2.8 +- 0.3 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+1.27 sec in the 15-150 keV band
is 1.0 +- 0.2 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level.

The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/1036139/BA/
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