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GCN Circular 11959

Subject
GRB 110422A: Swift-BAT refined analysis
Date
2011-04-22T18:14:12Z (13 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@lheamail.gsfc.nasa.gov>
D. M. Palmer (LANL), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC),
J. R. Cummings (GSFC/UMBC), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA),
V. Mangano (INAF-IASFPA), C. B. Markwardt (GSFC), T. Sakamoto (GSFC/UMBC),
M. Stamatikos (OSU), J. Tueller (GSFC), T. N. Ukwatta (MSU)
(i.e. the Swift-BAT team):
 
Using the data set from T-61 to T+195 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 110422A (trigger #451901)
(Mangano, et al., GCN Circ. 11957).  The BAT ground-calculated position is
RA, Dec = 112.057, 75.100 deg, which is 
   RA(J2000)  =  07h 28m 13.7s 
   Dec(J2000) = +75d 05' 58.8" 
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 22%.
 
The mask-weighted light curve shows several overlapping peaks starting
at ~T-15 sec, peaking at ~T+8 sec, and ending at ~T+60 sec.  At the 3-sigma
level, there is another peak from T+70 to T+115 sec.  T90 (15-350 keV)
is 25.9 +- 0.6 sec (estimated error including systematics).
 
The time-averaged spectrum from T-11.2 to T+40.3 sec is best fit by a power law
with an exponential cutoff.  This fit gives a photon index 0.86 +- 0.10, 
and Epeak of 149.4 +- 18.5 keV (chi squared 46.5 for 56 d.o.f.).  For this
model the total fluence in the 15-150 keV band is 4.1 +- 0.1 x 10^-5 erg/cm2
and the 1-sec peak flux measured from T+6.90 sec in the 15-150 keV band is
30.7 +- 1.0 ph/cm2/sec.  A fit to a simple power law gives a photon index
of 1.35 +- 0.00 (chi squared 118.3 for 57 d.o.f.).  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/451901/BA/
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