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GCN Circular 29611

GRB 210305A: Swift-BAT refined analysis
2021-03-07T13:13:21Z (3 years ago)
Takanori Sakamoto at AGU <>
H. A. Krimm (NSF), S. D. Barthelmy (GSFC), J. R. Cummings (CPI),
C. B. Markwardt (GSFC), 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+963 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 210305A (trigger #1035922)
(D'Ai, et al., GCN Circ. 29595).  The BAT ground-calculated position is
RA, Dec = 319.808, 34.548 deg which is
    RA(J2000)  =  21h 19m 13.9s
    Dec(J2000) = +34d 32' 52.8"
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 74%.
The BAT light curve showed a complex structure with a duration of about ~100 sec.
T90 (15-350 keV) is 68.6 +- 4.4 sec (estimated error including systematics).
The time-averaged spectrum from T-21.65 to T+71.76 sec is best fit by a power law
with an exponential cutoff.  This fit gives a photon index 0.93 +- 0.19,
and Epeak of 104.1 +- 19.7 keV (chi squared 43.93 for 56 d.o.f.).  For this
model the total fluence in the 15-150 keV band is 7.1 +- 0.2 x 10^-6 erg/cm2
and the 1-sec peak flux measured from T+0.26 sec in the 15-150 keV band is
3.4 +- 0.3 ph/cm2/sec.  A fit to a simple power law gives a photon index
of 1.49 +- 0.04 (chi squared 71.71 for 57 d.o.f.).  All the quoted errors
are at the 90% confidence level.
The results of the batgrbproduct analysis are available at
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