[vsnet-grb-info 3644] GRB 060825: Swift-BAT Refined Analysis

[GCN Circulars]

TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  5478
SUBJECT: GRB 060825: Swift-BAT Refined Analysis
DATE:    06/08/25 15:38:36 GMT
FROM:    Hans Krimm at NASA-GSFC  <krimm at milkyway.gsfc.nasa.gov>

E. Fenimore (LANL),  L. Barbier (GSFC),  S. Barthelmy (GSFC),
J. Cummings (GSFC/ORAU), N. Gehrels (GSFC), D. Hullinger (BYU-Idaho),
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-240 to T+614 sec from the recent telemetry
downlink, we report further analysis of Swift GRB 060825
(trigger #226382)  (Sato, et al., GCN Circ. 5471).  The BAT ground-calculated
position is (RA,Dec) = 18.130, 55.796 deg {1h 12m 31.3s, 55d 47' 44.7"} (J2000)
+- 0.7 arcmin, (radius, sys+stat, 90% containment).  The partial 
coding was 90%.

The mask-weighted light curve shows a single broad peak from T-4 sec to T+7 sec
T90 (15-350 keV) is 8.1 +- 1 sec (estimated error including systematics).

The time-averaged spectrum from T-4.2 to T+7.0 is best fit by
a power law with an exponential cutoff.  This fit gives a photon index
1.11 +- 0.32, and Epeak of 73 +- 18 keV (chi squared 54.91 for 56 d.o.f.).
For this model the total fluence in the 15-150 keV band is
9.8 +- 0.5 x 10^-7 erg/cm2 and the 1-sec peak flux measured from
T+0.07 sec in the 15-150 keV band is 2.7 +- 0.2 ph/cm2/sec.
A fit to a simple power law gives a photon index of 1.71 +- 0.07
(chi squared 67.23 for 57 d.o.f.).  All the quoted errors are at the 90%
confidence level.