[vsnet-grb-info 2049] GRB 050826: BAT refined analysis

[GCN Circulars]

TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  3888
SUBJECT: GRB 050826: BAT refined analysis
DATE:    05/08/26 21:17:04 GMT
FROM:    Craig Markwardt at NASA/GSFC/UMD  <craigm at milkyway.gsfc.nasa.gov>

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

Using the full data set, we report further analysis of Swift-BAT
GRB 050826 (trigger # 152113) (Mangano, et al., GCN 3884).  The
ground-analysis position is RA,Dec 87.772, -2.667 (J2000) with
an uncertainty of 2.1 arcmin (radius, 90%, stat+sys).  This is
2.7 arcmin from the onboard position and 1.7 arcmin from the XRT
position reported by Mangano et al. in GCN Circ. 3885.

The light curve shows a peak with a FRED structure lasting until T+14,
a second 4-sec peak centered at T+18, and possible lower-energy peaks
at T+34 sec and T+52 sec. The main part of the burst is weak and hard
in the BAT energy range. T90 is 35 +- 8 sec. Fitting a simple power
law over the interval from T+1 to T+36 sec, the photon index is
1.2 +/- 0.3 with a fluence of 4.3 +/- 0.7 x 10^-7 erg/cm^2 in the
15-150 keV band (90% c.l). The peak flux in a 1-second wide window
starting at T+1 sec is 0.42 +/- 0.12 ph/cm^2/sec (15-150 keV).