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GCN Circular 11811

Subject

GRB 110319A: Swift-BAT refined analysis

Date

2011-03-19T14:28:25Z (14 years ago)

From

Scott Barthelmy at NASA/GSFC <scott@lheamail.gsfc.nasa.gov>

S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC),
N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC),
A. Melandri (INAF-OAB), D. M. Palmer (LANL), 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-239 to T+963 sec from recent telemetry downlinks,
we report further analysis of BAT GRB 110319A (trigger #449578)
(Melandri, et al., GCN Circ. 11807Not found
 
 
).  The BAT ground-calculated position is
RA, Dec = 356.510, -66.008 deg, which is 
   RA(J2000)  =  23h 46m 02.4s 
   Dec(J2000) = -66d 00' 28.7" 
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 100%.
 
The mask-weighted light curve shows two overlapping peaks starting
at ~T_zero, peaking at ~T+5 and ~T+13 sec, and ending at ~T+30 sec.
T90 (15-350 keV) is 19.3 +- 1.6 sec (estimated error including systematics).
 
The time-averaged spectrum from T-0.3 to T+31.3 sec is best fit by a power law
with an exponential cutoff.  This fit gives a photon index 1.31 +- 0.43, 
and Epeak of 21.9 +- 7.0 keV (chi squared 54.2 for 56 d.o.f.).  For this
model the total fluence in the 15-150 keV band is 1.4 +- 0.1 x 10^-6 erg/cm2
and the 1-sec peak flux measured from T+13.10 sec in the 15-150 keV band is
2.2 +- 0.2 ph/cm2/sec.  A fit to a simple power law gives a photon index
of 2.55 +- 0.08 (chi squared 86.5 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/449578/BA/