GCN Circular 7925
Subject
GRB 080702A: Swift-XRT Team refined analysis
Date
2008-07-02T21:03:07Z (16 years ago)
From
Kim Page at U.of Leicester <kpa@star.le.ac.uk>
K.L. Page (U. Leicester) & M. De Pasquale (UCL-MSSL) report on behalf of
the Swift-XRT team:
We have analysed the first 3 orbits of Swift-XRT data obtained for GRB
080702A (De Pasquale et al., GCN Circ. 7920), covering 5.2 ks of Photon
Counting mode data, between ~75 and 12.6 ks after the trigger. The
UVOT-enhanced XRT position was given by Goad et al. in GCN Circ. 7923.
The light-curve can be modelled by a broken power-law, with a flat decay
of alpha = 0.5 +/- 0.3 until around the end of the first orbit of data. At
this point, the decay steepens to 1.6 +0.9/-0.3. The afterglow is already
faint by the end of the third orbit.
A spectrum extracted from the first orbit of data can be modelled with an
absorbed power-law, with Gamma = 2.05 +0.71/-0.64 and NH = (6.2
+5.4/-3.6)x10^21 cm^-2, in excess of the Galactic column in this direction
of 1.53x10^21 cm^-2. The observed (unabsorbed) flux over this time
interval (75-800 s post-trigger) is 5.7x10^-12 (1.0x10^-11) erg cm^-2
s^-1.
If the light-curve continues to decay with alpha ~ 1.6, the count rate 24
hours after the burst is estimated to be 3.3x10^-5 count s^-1, which
corresponds to an observed flux of 2x10^-15 erg cm^-2 s^-1.
This is an official product of the Swift-XRT team.