GCN Circular 8226
Subject
GRB 080913: Swift-XRT refined analysis
Date
2008-09-13T17:30:12Z (16 years ago)
From
Andy Beardmore at U Leicester <apb@star.le.ac.uk>
A.P. Beardmore (U. Leicester) and P. Schady (MSSL-UCL) report on behalf
of the Swift-XRT team :
The Swift-XRT started observing the field of GRB 080913 (trigger number
324561, Schady et al., GCN Circ. 8217) at 2008-09-13 06:48:30 UT, 94 s
after the trigger. The best XRT position is the UVOT-enhanced position
reported by Beardmore et al. (GCN Circ. 8219).
The X-ray light curve presently spans 5 orbits of photon counting mode
data from T+108 s to T+23 ks. The light curve shows a number of small
flares in the first orbit, with the largest giving a factor of ~7
increase in count rate at T+1.8 ks, on top of a power-law decay of
index 1.20 +0.16 -0.13.
A 2.7 ks exposure X-ray spectrum from T+108 s to T+7.6 ks can be well
fit by an absorbed power-law with a photon index of 1.69 +0.46 -0.41
and a column density consistent with the Galactic value of 3.2 x 10^20 cm^-2
in the direction of the burst. The observed 0.3-10.0 keV flux is
(3.2 +0.9 -1.6) x 10^-12 erg cm^-2 s^-1 which corresponds to an unabsorbed
flux of (3.7 +1.6 -1.7) x 10^-12 erg cm^-2 s^-1. The count to flux
conversion factor is 4.6 x 10^-11 erg cm^-2 count^-1.
Providing the source continues to decay at the same rate, we predict a
count rate of 2.8 x 10^-4 count s^-1 at T+1 day.
This circular is an official product of the Swift-XRT team.