[vsnet-grb-info 11856] GRB 120422A: Swift-BAT refined analysis

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  13246
SUBJECT: GRB 120422A: Swift-BAT refined analysis
DATE:    12/04/22 13:48:29 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott at lheamail.gsfc.nasa.gov>

S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC),
E. E. Fenimore (LANL), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA),
C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (GSFC/UMBC),
G. Sato (ISAS), M. Stamatikos (OSU), E. Troja (NASA/GSFC/ORAU),
J. Tueller (GSFC), T. N. Ukwatta (MSU)
(i.e. the Swift-BAT team):
 
Using the data set from T-61 to T+224 sec from recent telemetry downlinks,
we report further analysis of BAT GRB 120422A (trigger #520658)
(Troja, et al., GCN Circ. 13243).  The BAT ground-calculated position is
RA, Dec = 136.915, 13.974 deg, which is 
   RA(J2000)  =  09h 07m 39.7s 
   Dec(J2000) = +13d 58' 27.1" 
with an uncertainty of 2.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 68%.
 
The mask-weighted light curve shows a single peak starting at ~T-3 sec,
peaking at ~T+1, and ending at ~T+20 sec.  There is a low-significance peak
(~3 sigma) at T+45 to T+65.  T90 (15-350 keV) is 5.35 +- 1.4 sec
(estimated error including systematics).
 
The time-averaged spectrum from T-0.80 to T+6.00 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.19 +- 0.24.  The fluence in the 15-150 keV band is 2.3 +- 0.4 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T+0.86 sec in the 15-150 keV band
is 0.6 +- 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/520658/BA/