GCN Circular 12561
Subject
GRB 111117A: Swift-BAT refined analysis of a short hard burst
Date
2011-11-17T20:12:02Z (12 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@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 1.7 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/
[GCN OPS NOTE(17nov11): Per author's request, the missing position uncertainty
was added (1.7 arcmin).]