GRB 121031A: Swift-BAT refined analysis
S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC),
V. D'Elia (ASDC), E. E. Fenimore (LANL), N. Gehrels (GSFC),
H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC), D. M. Palmer (LANL),
T. Sakamoto (AGU), 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-61 to T+243 sec from recent telemetry downlinks,
we report further analysis of BAT GRB 121031A (trigger #537195)
(D'Elia, et al., GCN Circ. 13934). The BAT ground-calculated position is
RA, Dec = 170.772, -3.513 deg, which is
RA(J2000) = 11h 23m 05.2s
Dec(J2000) = -03d 30' 47.7"
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 100%.
The mask-weighted light curve shows a FRED-like peak with a couple smaller peaks
superposed. It starts at ~T-10 sec, peaks at ~T+4 sec, and ends at ~T+100 sec.
T90 (15-350 keV) is 62.5 +- 25.1 sec (estimated error including systematics).
The time-averaged spectrum from T-2.64 to T+98.31 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.59 +- 0.07. The fluence in the 15-150 keV band is 3.1 +- 0.1 x 10^-06 erg/cm2.
The 1-sec peak photon flux measured from T+4.10 sec in the 15-150 keV band
is 2.2 +- 0.2 ph/cm2/sec. All the quoted errors are at the 90% confidence
The results of the batgrbproduct analysis are available at