GCN Circular 3683
Subject
GRB 050726: early Swift XRT analysis results
Date
2005-07-26T16:08:12Z (19 years ago)
From
Alberto Moretti at Obs Brera Merate <moretti@merate.mi.astro.it>
A. Moretti (INAF-OAB), S. Campana (INAF-OAB), P. Romano (INAF-OAB), L.A.
Antonelli (INAF-OAR), M. Chester (PSU), P. Boyd (GSFC-UMBC) on behalf of
the Swift-XRT Team report.
We have analyzed the Swift XRT data from the first 3 orbit observation
of GRB 050726 (Bathelmy et al., GCN 3682). As already reported an
uncatalogued, fading X-ray source was detected by XRT at the following
position: RA,Dec 13h 20m 12.30s -32d 03m 50.8s} (J2000) with an
uncertainty of 6 arcsec (90% containment).
The observations in Windowed Timing (WT) and Photon Counting (PC) mode
start 132 and 334 seconds from the BAT trigger (T0) respectively.
A preliminary spectral fit (simple absorbed power-law) to the WT data
yields a photon index of 1.98-/+0.1 in the [0.5-10] keV band. The
derived NH is (1.3)E21 cm^-2, which is higher than the Galactic value
(0.4E+21 cm-2; Dickey & Lockman 1990). A preliminary spectral fitto the
PC data yields values well consistent with the WT data.
The light curve shows 2 highly significant flares in the first 200
seconds and then a monotonic fading which can be fitted with a power law
of slope 1.06+-0.10
The unabsorbed 0.5-10.0 keV flux at 24 hours after the burst is then
estimated to be 5E-13 ergs/s/cm2.