TITLE:   GCN CIRCULAR
NUMBER:  13996
SUBJECT: GRB 121125A: Swift-BAT refined analysis
DATE:    12/11/25 20:28:47 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott@lheamail.gsfc.nasa.gov>

S. D. Barthelmy (GSFC), B. N. Barlow (PSU), 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), 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-60 to T+243 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 121125A (trigger #539563)
(Barlow, et al., GCN Circ. 12993).  The BAT ground-calculated position is
RA, Dec = 228.519, 55.318 deg, which is 
   RA(J2000)  =  15h 14m 04.6s 
   Dec(J2000) = +55d 19' 03.5" 
with an uncertainty of 1.2 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 80%.
 
The mask-weighted light curve shows two clusters of overlapping peaks
that start at ~T-7 sec, peaks at ~T+37 sec, and ends at ~T+100 sec.
T90 (15-350 keV) is 52.2 +- 4.6 sec (estimated error including systematics).
 
The time-averaged spectrum from T-6.31 to T+77.64 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.52 +- 0.06.  The fluence in the 15-150 keV band is 4.7 +- 0.1 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+36.56 sec in the 15-150 keV band
is 2.9 +- 0.2 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/539563/BA/