[vsnet-grb-info 3111] GRB 060403: Refined analysis of the Swift-BAT burst

[GCN Circulars]

TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  4948
SUBJECT: GRB 060403:  Refined analysis of the Swift-BAT burst
DATE:    06/04/03 21:47:08 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <Scott at lheamail.gsfc.nasa.gov>

J. Tueller (GSFC), L. Barbier (GSFC), S.D. Barthelmy (GSFC),
J. Cummings (GSFC/NRC), E. Fenimore (LANL), N. Gehrels (GSFC),
D. Hullinger (BYU-Idaho), H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), 
J. Norris (GSFC), D. Palmer (LANL), A. Parsons (GSFC),
T. Sakamoto (GSFC/NRC), G. Sato (ISAS)
on behalf of the Swift-BAT team:

Using the data set from T-119 to T+183 sec from recent telemetry downlinks,
we report further analysis of BAT GRB 060403 (trigger #203755)
(Boyd, et al., GCN 4945).  The BAT ground-calculated position is RA,Dec =
282.336, 8.328 deg {18h 49m 20.7s, 8d 19' 39.8"} (J2000) +- 1.1 arcmin,
(radius, sys+stat, 90% containment).  The partial coding was 100%.
 
The mask-weighted light curve shows a single FRED-like peak starting at
T-8 sec and extending out to about T+32 sec.  T90 (15-350 keV) is
30 +- 3 sec (estimated error including systematics).
The spectral lags place this burst in the long-burst class
(Norris et al. 2005, ApJ, 627, 324):
1.23 +- 0.55 s (15-25 keV vs. 50-100 keV) and
0.80 +- 0.24 s (25-50 keV vs. 50-100 keV).
 
The time-averaged spectrum from T-6.2 to T+32.1 is best fit by 
a simple power-law model.  The power law index of the time-averaged
spectrum is 1.08 +- 0.09.  The fluence in the 15-150 keV band is
1.4 +- 0.1 x 10^-06 erg/cm2.  The 1-sec peak photon flux measured
from T-1.22 sec in the 15-150 keV band is 1.0 +- 0.1 ph/cm2/sec.
All the quoted errors are at the 90% confidence level.