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GCN Circular 7746

Subject
GRB 080517: Swift-XRT refined analysis
Date
2008-05-18T07:39:17Z (16 years ago)
From
Phil Evans at U of Leicester <pae9@star.le.ac.uk>
P. A. Evans (U. Leicester) and A.M. Parsons (GSFC) report on behalf of the 
Swift-XRT team:

We have analysed the first two snapshots of Swift-XRT data obtained for 
GRB 080517 (Parsons et al, GCN Circ. 7742), comprising 3.3 ks in Photon 
Counting (PC) mode, starting 144 s after the BAT trigger. The 
UVOT-enhanced XRT position was given in Evans et al. (GCN Circ. 7744)

The light curve can be described as a broken power-law, with an initial
decay of 2.47 (+0.25/-0.23), with a break at T+~1100s to a slope of 0.57
(+0.25/-0.74).

A spectrum obtained from all of the PC data can be modelled with an
absorbed power-law, with gamma=1.91 (+0.36/-0.34) and an absorption
column of 1.41 (+0.10/1.11) e21 cm^-2, in excess of the Galactic
value of 8.12e20 cm^-2 (Kalberla et al. 2005). The observed
(unabsorbed) flux in this spectrum is 6.07 (8.12) e-12 erg cm^-2
s^-1. The counts to  observed flux conversion is 5.93e-11 erg cm^-2
count^-1.

If the light-curve continues to decay at alpha=0.57  the count rate at 
24 hours is predicted to be 1.6e-3 count s-1, corresponding to an 
observed (unabsorbed) flux of 7.10 (9.49) e-14 erg cm^-2 s^-1.

This is an official product of the Swift-XRT team.
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