[vsnet-grb-info 12484] GRB 121011A, Swift-BAT refined analysis

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  13852
SUBJECT: GRB 121011A, Swift-BAT refined analysis
DATE:    12/10/11 21:14:11 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott at lheamail.gsfc.nasa.gov>

M. Stamatikos (OSU), 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),
J. L. Racusin (NASA/GSFC), T. Sakamoto (AGU), G. Sato (ISAS),
J. Tueller (GSFC), T. N. Ukwatta (MSU)
(i.e. the Swift-BAT team):
 
Using the data set from T-60 to T+243 sec from recent telemetry downlinks,
we report further analysis of BAT GRB 121011A (trigger #535764)
(Racusin, et al., GCN Circ. 13845).  The BAT ground-calculated position is
RA, Dec = 260.204, 41.123 deg, which is 
   RA(J2000)  =  17h 20m 49.0s 
   Dec(J2000) = +41d 07' 22.4" 
with an uncertainty of 1.8 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 32%.
 
The mask-weighted light curve shows a single pulse starting at ~T-9 sec,
peaking at ~T+1 sec, and ending at ~T+110 or ~T+150 sec.
T90 (15-350 keV) is 75.6 +- 12.7 sec (estimated error including systematics).
 
The time-averaged spectrum from T-7.45 to T+80.10 sec is best fit by a power law
with an exponential cutoff.  This fit gives a photon index 0.10 +- 0.73, 
and Epeak of 101.5 +- 42.2 keV (chi squared 40.6 for 56 d.o.f.).  For this
model the total fluence in the 15-150 keV band is 2.7 +- 0.7 x 10^-6 erg/cm2
and the 1-sec peak flux measured from T-0.69 sec in the 15-150 keV band is
1.2 +- 0.3 ph/cm2/sec.  A fit to a simple power law gives a photon index
of 1.20 +- 0.14 (chi squared 49.2 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/535764/BA/