GCN Circular 8657
Subject
GRB 081211: Swift XRT refined analysis
Event
Date
2008-12-11T22:08:03Z (18 years ago)
From
Rhaana Starling at U of Leicester <rlcs1@star.le.ac.uk>
R.L.C. Starling (U. Leicester) and H.A. Krimm (CRESST/GSFC/USRA) report on
behalf of the Swift XRT team:
We have analysed data from the first 2 orbits of Swift XRT observations of
GRB 081211 (trigger=337115, Krimm et al. GCN Circular 8653) from 113 s to
24 ks after the BAT trigger, all collected in Photon Counting (PC) mode.
The enhanced Swift XRT position for this GRB is given in Beardmore et al.
(GCN Circular 8655).
We confirm that the source is fading, however, the light curve is not well
constrained at present. A power law fit results in a decay slope of
alpha=0.6+/-0.1, but we note that flaring may be present from 350-1000 s.
The time-averaged spectrum can be fit with an absorbed power law with
photon index Gamma=2.4+/-0.3. There is significant absorption above the
Galactic value (nH_Gal=1.9e20 cm^-2, Kalberla et al. 2005) amounting to a
column of nH=(1.2+/-0.6)e21 cm^-2 (at z=0). The observed (unabsorbed)
0.3-10 keV flux is 3.1 (5.0) e-12 erg cm^-2 s^-1. The observed
(unabsorbed) count rate to flux conversion derived from this spectrum is 1
count s^-1 = 3.3 (5.3) e-11 erg cm^-2.
The predicted count rate at T+24h, assuming a decay of alpha=0.6, is 0.01
count s^-1.
The results of the XRT automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00337115.
This circular is an official product of the Swift-XRT team.