[vsnet-grb-info 3569] GRB 060805: Swift-BAT Refined Analysis

[GCN Circulars]

TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  5403
SUBJECT: GRB 060805: Swift-BAT Refined Analysis
DATE:    06/08/05 16:28:08 GMT
FROM:    Hans Krimm at NASA-GSFC  <krimm at milkyway.gsfc.nasa.gov>

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

Using the data set from T-240 to T+963 sec from the recent telemetry
downlink, we report further analysis of BAT GRB 060805
(trigger #222683)  (Ziaeepour, et al., GCN Circ. 5398).  The BAT
ground-calculated position is (RA,Dec) = 220.925, 12.576 deg
{14h 43m 41.9s, 12d 34' 35.0"} (J2000) +- 2.7 arcmin,
(radius, sys+stat, 90% containment).  The partial coding was 96%.

The currently available event data record has several gaps, most significantly
from T+14.3 to T+19.5 sec. Based on the available data, the mask weighted light
curve shows a single peak with a roughly square profile and a duration
of ~6 sec.  Emission was only seen below 100 keV, which is consistent with the
very soft spectrum found. T90 (15-350 keV) is 5.4 +- 0.5 sec (estimated error
including systematics).

The time-averaged spectrum from T-1.6 to T+4.7 is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
2.23 +- 0.42. The fluence in the 15-150 keV band is 7.4 +- 2.0 x 10^-8 erg/cm2.
The 1-sec peak photon flux measured from T+0.71 sec in the 15-150 keV
band is 0.3 +- 0.1 ph/cm2/sec.  All the quoted errors are at the 90%
confidence level.