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GCN Circular 12671

Subject

GRB 111212A: Swift-BAT refined analysis

Date

2011-12-12T14:55:22Z (13 years ago)

From

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

T. N. Ukwatta (MSU) S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC),
S. Campana (INAF-OAB), 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), J. Tueller (GSFC), (i.e. the Swift-BAT team):
 
Using the data set from T-240 to T+962 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 111212A (trigger #509543)
(Campana, et al., GCN Circ. 12667Loading...
 
 ).  The BAT ground-calculated position is
RA, Dec = 310.442, -68.585 deg, which is 
   RA(J2000)  =  20h 41m 46.0s 
   Dec(J2000) = -68d 35' 04.5" 
with an uncertainty of 1.8 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 35%.
 
The mask-weighted light curve shows a FRED-like pulse starting at ~T-2 sec,
peaking at ~T+6 sec, and returning to background around T+60 sec.  Since
Swift slewed due to an observing constraint, the burst location left
the BAT FoV at ~T+70 sec, so we can not say if there was further actitivty
in the lightcurve.
 
The time-averaged spectrum from T-5.77 to T+62.74 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.67 +- 0.18.  The fluence in the 15-150 keV band is 1.4 +- 0.2 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+4.76 sec in the 15-150 keV band
is 0.8 +- 0.3 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/509543/BA/