[vsnet-grb-info 12546] GRB 121027A: Swift-BAT refined analysis

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  13910
SUBJECT: GRB 121027A: Swift-BAT refined analysis
DATE:    12/10/27 14:44:48 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott at lheamail.gsfc.nasa.gov>

S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC),
P. A. Evans (U Leicester), 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 the recent telemetry downlink,
we report further analysis of BAT GRB 121027A (trigger #536831)
(Evans, et al., GCN Circ. 13906 (not 13907)).  The BAT ground-calculated position is
RA, Dec = 63.598, -58.839 deg, which is 
   RA(J2000)  =  04h 14m 23.5s 
   Dec(J2000) = -58d 50' 21.3" 
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 80%.
 
The mask-weighted light curve shows a FRED with two small peaks on the tail,
starting at ~T-9 sec, peaking at ~T+3 sec, with a long tail out to
~T+105 sec (or possibly to ~T+165 sec).  T90 (15-350 keV) is 62.6 +- 4.8 sec
(estimated error including systematics).
 
The time-averaged spectrum from T-9.34 to T+65.33 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.82 +- 0.09.  The fluence in the 15-150 keV band is 2.0 +- 0.1 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+2.00 sec in the 15-150 keV band
is 1.3 +- 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/536831/BA/