[vsnet-grb-info 11149] GRB 111117A: Swift-BAT refined analysis of a short hard burst

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  12561
SUBJECT: GRB 111117A: Swift-BAT refined analysis of a short hard burst
DATE:    11/11/17 20:12:02 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott at lheamail.gsfc.nasa.gov>

T. Sakamoto (GSFC/UMBC), 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), V. Mangano (INAF-IASFPA),
J. Norris (BSU), D. M. Palmer (LANL), G. Sato (ISAS), M. Stamatikos (OSU),
J. Tueller (GSFC), T. N. Ukwatta (MSU)
(i.e. the Swift-BAT team):
 
Using the data set from T-240 to T+395 sec from recent telemetry downlinks,
we report further analysis of BAT GRB 111117A (trigger #507901)
(Mangano, et al., GCN Circ. 12559).  The BAT ground-calculated position is
RA, Dec = 12.702, 23.021 deg, which is 
   RA(J2000)  =   00h 50m 49.9s
   Dec(J2000) =  +23d 00' 11.0"
with an uncertainty of  arcmin, (radius, sys+stat, 90% containment).
The partial coding was 100%.
 
The mask-weighted light curve shows two peaks, the first starts at ~T+0.00,
peaks at ~T+0.15 and ends at ~T+0.30 sec.  The second starts at ~T+0.35,
peaks at ~T+0.50, and ends at ~T+0.60 sec.  T90 (15-350 keV) is 0.47 +- 0.09 sec
(estimated error including systematics).

The spectral lag is 0.6 +/- 2.4 msec using the 100-350 and 25-50 keV bands
with 4-ms binning of the raw lightcurves.  This clearly indicates a short burst.
 
The time-averaged spectrum from T-0.016 to T+0.520 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
0.65 +- 0.22.  The fluence in the 15-150 keV band is 1.40 +- 0.18 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T+0.00 sec in the 15-150 keV band
is 1.35 +- 0.20 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/507901/BA/