[vsnet-grb-info 4391] GRB 070306, Swift-BAT refined analysis

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  6173
SUBJECT: GRB 070306, Swift-BAT refined analysis
DATE:    07/03/06 23:50:38 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott at lheamail.gsfc.nasa.gov>

S. D. Barthelmy (GSFC), L. Barbier (GSFC), J. Cummings (GSFC/UMBC),
E. Fenimore (LANL), N. Gehrels (GSFC), H. Krimm (GSFC/USRA),
C. Markwardt (GSFC/UMD), D. Palmer (LANL), S. B. Pandey (UCL-MSSL),
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-240 to T+962 sec from recent telemetry downlinks,
we report further analysis of BAT GRB 070306 (trigger #263361)
(Pandy, et al., GCN Circ. 6169).  The BAT ground-calculated position is
RA, Dec = 148.097, +10.477 deg which is 
   RA(J2000)  = 09h 52m 23.3s 
   Dec(J2000) = 10d 28' 37.2" 
with an uncertainty of 2.4 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 28%.
 
The mask-weighted lightcurve shows a small precursor peak starting
at T-120 through T-105 sec.  Then a second pulse (of equal amplitude)
starting at ~T-15 sec and exponentially decaying back to background
at ~T+50 sec.  Then a much larger peak starting at ~T+75 sec,
exponentially rising to a peak at T+98 sec, end then exponentially
decaying to background at ~T+220 sec.  T90 (15-350 keV) is 210 +- 10 sec
(estimated error including systematics).
 
The time-averaged spectrum from T-118.8 to T+186.5 is best fit by a
simple power-law model.  The power law index of the time-averaged
spectrum is 1.72 +- 0.10.  The fluence in the 15-150 keV band is
5.5 +- 0.3 x 10^-6 erg/cm2.  The 1-sec peak photon flux measured
from T+98.27 sec in the 15-150 keV band is 4.2 +- 0.2 ph/cm2/sec.
All the quoted errors are at the 90% confidence level.