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GCN Circular 27650

Subject
GRB 200425A: Swift-BAT refined analysis
Date
2020-04-26T00:21:17Z (4 years ago)
From
Amy Lien at GSFC <amy.y.lien@nasa.gov>
C. B. Markwardt (GSFC), S. D. Barthelmy (GSFC),
M. G. Bernardini (INAF-OAB),  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-240 to T+962 sec from the recent telemetry
downlink,
we report further analysis of BAT GRB 200425A (trigger #967774)
(Bernardini et al., GCN Circ. 27638).  The BAT ground-calculated position is
RA, Dec = 85.217, -13.399 deg which is
   RA(J2000)  =  05h 40m 52.2s
   Dec(J2000) = -13d 23' 58.1"
with an uncertainty of 2.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 100%.

The mask-weighted light curve shows a weak pulse that starts at ~T-10 s,
peaks at ~T+3 s, and ends at ~T+10 s. In addition, there is some weak
emission that starts at ~T-50 s and lasts till ~T+60 s. T90 (15-350 keV)
is 81.0 +- 21.7 sec (estimated error including systematics).

The time-averaged spectrum from T-47.59 to T+58.41 sec is best fit by a
simple
power-law model.  The power law index of the time-averaged spectrum is
1.30 +- 0.21.  The fluence in the 15-150 keV band is 1.2 +- 0.2 x 10^-6
erg/cm2.
The 1-sec peak photon flux measured from T+2.41 sec in the 15-150 keV band
is 0.7 +- 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/967774/BA/
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