[vsnet-grb-info 4434] GRB 070318, Swift-BAT refined analysis

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  6212
SUBJECT: GRB 070318, Swift-BAT refined analysis
DATE:    07/03/18 13:59:03 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott at lheamail.gsfc.nasa.gov>

J. Cummings (GSFC/UMBC), L. Barbier (GSFC), S. D. Barthelmy (GSFC),
E. Fenimore (LANL), N. Gehrels (GSFC), H. Krimm (GSFC/USRA),
C. Markwardt (GSFC/UMD), D. Palmer (LANL), A. Parsons (GSFC),
T. Sakamoto (GSFC/ORAU), G. Sato (GSFC/ISAS), M. Stamatikos (GSFC/ORAU),
J. Tueller (GSFC)
on behalf of the Swift-BAT team:
 
Using the data set from T-120 to T+302 sec from recent telemetry downlinks,
we report further analysis of BAT GRB 070318 (trigger #271019)
(Cummings, et al., GCN Circ. 6210).  The BAT ground-calculated position is
RA, Dec = 48.486, -42.950 deg  which is 
   RA(J2000)  =  03h 13m 56.6s 
   Dec(J2000) = -42d 57' 1.1" 
with an uncertainty of 0.8 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 80%.
 
The mask-weighted lightcurve is a single FRED peak starting at ~T-10sec,
peaking at ~T+2 sec, and returning to background at around T+120 sec.
There is the possibility of weak peaks at ~T+140 and T+170 sec at the 
~3-sigma level.  T90 (15-350 keV) is 63 +- 3 sec (estimated error
including systematics).
 
The time-averaged spectrum from T-1.0 to T+89.4 is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.44 +- 0.08.  The fluence in the 15-150 keV band is 2.3 +- 0.1 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+1.94 sec in the 15-150 keV band
is 1.6 +- 0.2 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level.