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GCN Circular 7578

Subject
GRB 080409: Swift XRT refined analysis
Date
2008-04-09T11:53:54Z (16 years ago)
From
Rhaana Starling at U of Leicester <rlcs1@star.le.ac.uk>
R.L.C. Starling, P.A. Evans, K.L. Page (U. Leicester) and S.T. Holland 
(CRESST/USRA/GSFC) report, on behalf of the Swift XRT team:

We have analysed the first three orbits of Swift XRT data (5.8 ks of data 
from T0+96s to T0+1.29e4s) for GRB 080409 (Holland et al., GCN Circ. 
7573). The enhanced position for the X-ray afterglow is given in Evans et 
al. (GCN Circ. 7575).

The light curve shows an initial increase with slope of alpha1~0.6 up to
T~480s. The light curve then turns over to decay with a slope of
alpha2=-0.8+/-0.1.  

The Photon Counting mode spectrum collected from the first three orbits 
can be fit with an absorbed power law of photon index Gamma=2.2+0.5/-0.7 
and a total absorbing column of NH=(5 +5/-4)e21 cm-2, exceeding the 
Galactic value of 2.4e21 cm-2. The 0.3-10 keV observed (unabsorbed) flux 
is 3.2e-12 (6.7e-12) erg/cm2/s, corresponding to a count rate of 5.8e-2 
count/s and a count rate to flux conversion of 1 count/s = 5.6e-11 erg/cm2/s.

The predicted count rates at T0+24h and T0+48h are 6.8e-3 and 4.0e-3 
count/s respectively, assuming the decay continues with alpha=-0.8.

This is an official product of the Swift XRT team.
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