TITLE:   GCN CIRCULAR
NUMBER:  12963
SUBJECT: GRB 120218A: Swift-BAT refined analysis
DATE:    12/02/18 14:51:35 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott@lheamail.gsfc.nasa.gov>

S. D. Barthelmy (GSFC), T. Sakamoto (GSFC/UMBC), 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),
G. Sato (ISAS), M. Stamatikos (OSU), J. Tueller (GSFC),
T. N. Ukwatta (MSU), C. A. Wolf (PSU)
(i.e. the Swift-BAT team):
 
Using the data set from T-239 to T+303 sec from recent telemetry downlinks,
we report further analysis of BAT GRB 120218A (trigger #515277)
(Wolf, et al., GCN Circ. 12962).  The BAT ground-calculated position is
RA, Dec = 319.7641, -25.4626 deg which is
   RA(J2000)  =  21h 19m 03.4s
   Dec(J2000) = -25d 27' 45.4"
with an uncertainty of 1.9 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 4%.

The mask-weighted light curve shows 3 or 4 overlapping peaks starting
at ~T-28 sec, with the highest peak is at ~T+3 sec, and ending at ~T+15 sec.
T90 (15-350 keV) is 27.5 +- 1.0 sec (estimated error including systematics).
 
The time-averaged spectrum from T-20.6 to T+8.9 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.75 +- 0.11.  The fluence in the 15-150 keV band is 5.3 +- 0.4 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+2.33 sec in the 15-150 keV band
is 9.1 +- 1.2 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/515277/BA/