GCN Circular 14052
Subject
GRB 121209A: Swift-BAT refined analysis
Date
2012-12-10T12:40:00Z (11 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@lheamail.gsfc.nasa.gov>
T. N. Ukwatta (MSU), 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), A. Maselli (INAF-IASFPA),
D. M. Palmer (LANL), T. Sakamoto (AGU), G. Sato (ISAS),
M. Stamatikos (OSU), J. Tueller (GSFC)
(i.e. the Swift-BAT team):
Using the data set from T-60 to T+243 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 121209A (trigger #540964)
(Maselli, et al., GCN Circ. 14045). The BAT ground-calculated position is
RA, Dec = 326.800, -8.232 deg, which is
RA(J2000) = 21h 47m 12.0s
Dec(J2000) = -08d 13' 55.8"
with an uncertainty of 1.7 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 60%.
The mask-weighted light curve shows multiple peaks starting at ~T-5 sec,
max peak at ~T+28 sec, and ending at ~T+80 sec. T90 (15-350 keV) is
42.7 +- 2.0 sec (estimated error including systematics).
The time-averaged spectrum from T-2.16 to T+44.28 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.43 +- 0.08. The fluence in the 15-150 keV band is 2.9 +- 0.1 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+27.91 sec in the 15-150 keV band
is 3.4 +- 0.3 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/540964/BA/