TITLE:   GCN CIRCULAR
NUMBER:  11804
SUBJECT: GRB 110318B: Swift-BAT refined analysis
DATE:    11/03/18 21:01:05 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott@lheamail.gsfc.nasa.gov>

C. B. Markwardt (GSFC), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC),
J. R. Cummings (GSFC/UMBC), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA),
R. Margutti (INAF-OAB), D. M. Palmer (LANL), T. Sakamoto (GSFC/UMBC),
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 110318B (trigger #449549)
(Margutti, et al., GCN Circ. 11799).  The BAT ground-calculated position is
RA, Dec = 211.691, -51.577 deg, which is 
   RA(J2000)  =  14h 06m 45.9s 
   Dec(J2000) = -51d 34' 35.7" 
with an uncertainty of 1.7 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 85%.
 
The mask-weighted light curve shows a single peak starting at ~T-2 sec,
peaking at ~T+1 sec, and ending at ~T+5 sec.  T90 (15-350 keV) is
4.8 +- 0.6 sec (estimated error including systematics).
 
The time-averaged spectrum from T-1.7 to T+3.7 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.09 +- 0.17.  The fluence in the 15-150 keV band is 2.9 +- 0.3 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T+0.76 sec in the 15-150 keV band
is 0.7 +- 0.1 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/449549/BA/