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GCN Circular 22675

Subject
GRB 180425A: Swift-BAT refined analysis
Date
2018-04-25T14:53:09Z (6 years ago)
From
Hans Krimm at NSF/NASA-GSFC <hkrimm@nsf.gov>
T. Sakamoto (AGU), S. D. Barthelmy (GSFC),  J. R. Cummings (CPI),
H. A. Krimm (NSF/USRA), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC),
F. E. Marshall (NASA/GSFC), D. M. Palmer (LANL), 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 180425A (trigger #828672)
(Marshall, et al., GCN Circ. 22672).  The BAT ground-calculated position is
RA, Dec = 64.450, -32.949 deg which is
  RA(J2000)  =  04h 17m 48.1s
  Dec(J2000) = -32d 56' 58.1"
with an uncertainty of 1.5 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 27%.

The mask-weighted light curve shows a single triangular shaped peak beginning
at T-2 sec, peaking at T+3 sec and declining to background by T+14 sec.
T90 (15-350 keV) is 11.2 +- 2.6 sec (estimated error including systematics).

The time-averaged spectrum from T+0.06 to T+12.73 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.35 +- 0.13.  The fluence in the 15-150 keV band is 1.1 +- 0.1 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+2.33 sec in the 15-150 keV band
is 2.2 +- 0.3 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/828672/BA/
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