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GCN Circular 17330

Subject
GRB 150120B: Swift-BAT refined analysis
Date
2015-01-20T22:51:16Z (9 years ago)
From
Amy Lien at GSFC <amy.y.lien@nasa.gov>
C. B. Markwardt (GSFC), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC),
J. R. Cummings (GSFC/UMBC), V. D'Elia (ASDC) N. Gehrels (GSFC),
H. A. Krimm (GSFC/USRA), A. Y. Lien (GSFC/UMBC), D. M. Palmer (LANL),
T. Sakamoto (AGU), M. Stamatikos (OSU), J. Tueller (GSFC),
T. N. Ukwatta (LANL) (i.e. the Swift-BAT team):

Using the data set from T-61 to T+242 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 150120B (trigger #627170)
(V. D'Elia, et al., GCN Circ. 17314).  The BAT ground-calculated position is
RA, Dec = 39.309, 8.064 deg which is
  RA(J2000)  =  02h 37m 14.1s
  Dec(J2000) = +08d 03' 50.3"
with an uncertainty of 2.3 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 35%.

The mask-weighted light curve shows a multi-peaked structure starts at ~ T-20 s
and ends at ~ T+10 s, with the main peak at ~ T+0 s. T90 (15-350 keV)
is 24.30 +- 3.39 sec (estimated error including systematics).

The time-averaged spectrum from T-17.64 to T+9.63 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
2.20 +- 0.25.  The fluence in the 15-150 keV band is 5.4 +- 0.8 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T+0.58 sec in the 15-150 keV band
is 1.2 +- 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/627170/BA/
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