TITLE:   GCN CIRCULAR
NUMBER:  10313
SUBJECT: GRB 100103A: Swift-XRT team refined analysis 
DATE:    10/01/06 13:49:35 GMT
FROM:    Kim Page at U.of Leicester  <kpa@star.le.ac.uk>

K.L. Page (U. Leicester) and W.H. Baumgartner (GSFC/UMBC) report on behalf 
of the Swift-XRT team: 

We have analysed 8 ks of XRT data for the INTEGRAL GRB 100103A (Gotz et 
al. GCN Circ. 10307) obtained during two observations, from 3.3-10.3 ks 
and 196-224 ks after the trigger. The source found by Kennea & Baumgartner 
(GCN Circ. 10308; improved position given by Page et al. in GCN Circ. 
10312) is now clearly fading, with a decay slope of alpha = 0.87 (+0.14, 
-0.10). We therefore confirm that this is, indeed, the X-ray afterglow.

A spectrum formed from the PC mode data can be fitted with an absorbed 
power-law with a photon spectral index of 2.86 (+0.32, -0.30). The 
best-fitting absorption column is 6.5 (+1.3, -0.7) x 10^21 cm^-2, in 
excess of the Galactic value of 2.4 x 10^21 cm^-2 (Kalberla et al. 2005). 
The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor 
deduced from this spectrum is 3.9 x 10^-11 (1.7 x 10^-10) erg cm^-2 
count^-1. 

The results of the XRT-team automatic analysis are available at 
http://www.swift.ac.uk/xrt_products/00020125.

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