GCN Circular 3983
Subject
GRB 050915: Swift XRT refined analysis
Event
Date
2005-09-15T18:14:14Z (20 years ago)
From
Dirk Grupe at PSU/Swift-XRT <grupe@astro.psu.edu>
D. Grupe, J. Kennea, D. Burrows (PSU), and N. Gehrels GSFC) on report
behalf of the Swift XRT team:
We have analyzed the Swift XRT data of the first three orbits of GRB050915
(Grupe et al. GCN 3977, BAT trigger 155242). The new refined position
based
on the SDC quicklook data is:
RA (J2000) = 05h26m44.6s
DEC(J2000) = -28d01m01.0s
This position is 5.8 arcsec away from the XRT position reported by
Kennea et al.
(GCN 3979) based on the preliminary data analysis and 29 arcsec from the
refined BAT position (Barthelmy et al., GCN 3982).
The WT data show a spectrum that can be fitted by a single power law
with excess
absorption above the Galactic value. The X-ray energy spectral slope is
beta-x =
1.33+/-0.23. The integrated 0.3-10.0 keV Flux during the WT observation
was
4.6e-10 ergs/s/cm2 (corrected for absorption).
The XRT light curve started 87s after the burst and shows a rapidly
decaying
source after a light increased in flux at the beginning. The decay
slope is
alpha-1 = 3.00+/-0.14. The light curves shows a clear break in the PC
mode data
at 210s after the burst and flattens to a decay slope alpha-2=0.75 �0.04.
Extrapolating this light curve we estimate the 0.3-10.0 flux to be in
the order
of 5e-13 ergs/s/cm2 24 hours after the burst. However, this estimate
does not
take any late time break, which are usually observed in GRBs several
hours after
the burst, into consideration.