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GCN Circular 10165

Subject

GRB 091112: Swift-BAT refined analysis

Date

2009-11-13T04:20:04Z (15 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), E. E. Fenimore (LANL), N. Gehrels (GSFC),
H. A. Krimm (GSFC/USRA), V. Mangano (INAF-IASFPA), C. B. Markwardt (GSFC/UMD),
A. M. Parsons (GSFC), T. Sakamoto (GSFC/UMBC), G. Sato (ISAS),
M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC), T. N. Ukwatta (GWU)
(i.e. the Swift-BAT team):
 
Using the data set from T-60 to T+483 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 091112 (trigger #375659)
(Mangano, et al., GCN Circ. 10162Loading...
 
 ).  The BAT ground-calculated position is
RA, Dec = 257.751, -36.729 deg, which is 
   RA(J2000)  =  17h 11m 00.2s 
   Dec(J2000) = -36d 43' 43.4" 
with an uncertainty of 1.5 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 40%.
 
The mask-weighted light curve shows a roughly symmetric peak starting
at ~T-15 sec, peaking at ~T+2 sec, and ending at ~T+40 sec.
T90 (15-350 keV) is 17 +- 4 sec (estimated error including systematics).
 
The time-averaged spectrum from T-10.0 to T+14.7 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.03 +- 0.14.  The fluence in the 15-150 keV band is 2.1 +- 0.4 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+0.56 sec in the 15-150 keV band
is 1.9 +- 0.5 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/375659/BA/