TITLE:   GCN CIRCULAR
NUMBER:  8070
SUBJECT: GRB 080804: Swift-XRT Refined Analysis
DATE:    08/08/05 20:24:05 GMT
FROM:    Judith Racusin at PSU  <racusin@astro.psu.edu>

J. Racusin, C. Pagani (PSU) report on behalf of the Swift-XRT team:

We have analysed the first five orbits of Swift-XRT data available for GRB 
080804 (Racusin et al., GCN 8057) consisting of 123 s of WT mode data, and 
11.0 ks of PC mode data.  The enhanced XRT position is given in Beardmore 
et al. (GCN Circ. 8066).

The preliminary 0.3-10.0 keV lightcurve can be fit with a single power-law 
with a decay index of 1.09+/-0.03.

The WT and PC spectra can be jointly fit with an absorbed power-law with a 
photon index of 1.6 +/- 0.2.  The intrinsic absorption is at a level of 
1.7e21 cm^-2 (using z=2.2045, Thoene et al., GCN Circ. 8058), in addition 
to the Galactic absorption along the line of sight (1.6e20 cm^-2, Kalberla 
et al. 2005).  The average observed (unabsorbed) flux is 2.5e-10 (2.6e-10) 
ergs cm^-2 s^-1 and 1.2e-11 (1.2e-11) ergs cm^-2 s^-1, for the WT and PC 
spectra respectively.

Assuming the X-ray emission continues to decline at the same rate, we 
predict a 0.3-10.0 keV XRT count rate of 0.008 counts/s at T+24hr, which 
corresponds to an observed flux of 3.4e-13 ergs cm^-2 s^-1.

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