TITLE:   GCN CIRCULAR
NUMBER:  8087
SUBJECT: GRB 080810: Swift-XRT Team refined analysis 
DATE:    08/08/10 23:53:16 GMT
FROM:    Kim Page at U.of Leicester  <kpa@star.le.ac.uk>

K.L. Page (U. Leicester) reports on behalf of the Swift-XRT team:

We have analysed the first four orbits of the XRT data obtained for GRB 
080810 (Page et al., GCN Circ. 8080). The first orbit (376 s) was taken 
entirely in Windowed Timing (WT) mode, followed by 2.8 of Photon Counting 
(PC) data. The UVOT-enhanced position was given by Evans et al. in GCN 
Circ. 8086.

The WT data show a number of flares, with the strongest peaking around 107 
and 209 s after the trigger; the first of these is also visible in the BAT 
data. The PC data in later orbits can be modelled with a single power-law 
decay, with alpha = 1.20 +0.12/-0.11.

There is strong spectral evolution throughout the first orbit, as is 
typical for flaring activity. A spectrum extracted from the PC mode data 
(3.8-12.1 ks after the trigger) can be fitted with a power-law of Gamma = 
1.98 +/- 0.06, absorbed by the Galactic column in this direction of 
3.28x10^20 cm^-2. The observed (unabsorbed) flux over this time is 1.99 
(2.20) x 10^-11 erg cm^-2 s^-1.

If the decay continues with alpha = 1.2, the predicted count-rate at 24 
hours is 0.02 count s^-1, corresponding to an observed (unabsorbed) flux 
of 8.5 (9.4) x 10^-13 erg cm^-2 s^-1.

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