GCN Circular 12628
Subject
GRB 111208A found in ground analysis of BAT data
Date
2011-12-08T16:35:58Z (13 years ago)
From
Takanori Sakamoto at NASA/GSFC <takanori@milkyway.gsfc.nasa.gov>
T. Sakamoto (GSFC/UMBC), C. Graziani (U of Chicago), J. R. Cummings (GSFC/UMBC),
S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), E. E. Fenimore (LANL),
N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC),
D. M. Palmer (LANL), G. Sato (ISAS), M. Stamatikos (OSU), J. Tueller (GSFC),
T. N. Ukwatta (MSU)
(i.e. the Swift-BAT team):
Automated BAT ground analysis found a burst that occurred at 08:28:11 UT
with a significance of 10.1 sigma (15-200 keV) from the failed event data
of trigger #509285. The event is temporally coincident with the Fermi GBM
345025692. The best BAT location is RA, Dec = 290.2151, +40.6686 deg, which is
RA(J2000) = 19h 20m 51.6s
Dec(J2000) = +40d 40' 07.0"
with an uncertainty of 2.2 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 10%.
The mask-weighted light curve created from the failed event data
(available from 08:28:12 to 08:28:22 UT) shows a constant positive
rate from the beginning of the data and then decaying at 08:28:20 UT.
From the BAT raw light curve, the duration of the event is ~20 sec long.
The spectrum extracted using the full event data is best fit by a simple
power-law model. The power law index of the spectrum is 1.5 +- 0.3. The
fluence in 15-150 keV band measured from the 10 sec long event data is
9.8 +- 1.8 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from
08:28:19 UT is 1.3 +- 0.7 ph/cm2/sec. All the quoted errors are at the
90% confidence level.
Swift ToO observation of this burst has been scheduled.