TITLE:   GCN CIRCULAR
NUMBER:  8612
SUBJECT: Swift-XRT observations of GRB 081203B 
DATE:    08/12/04 16:44:11 GMT
FROM:    Boris Sbarufatti at INAF-IASF-Pa  <sbarufatti@ifc.inaf.it>

B. Sbarufatti, V. La Parola, V. Mangano (INAF IASF-Pa) report on  
behalf of the Swift-XRT team.

We report on Swift-XRT observations of GRB 081203B (Copete et al. GCN  
Circ. 8600,8602). We analyzed 3.2 ks of Photon Counting mode data for  
this burst, covering times from T+17 ks to T+ 47 ks. The source  
reported in Sbarufatti et al. (GCN Circ. 8605) and confirmed as the  
afterglow by Schady et al. (GCN Circ. 8606) is fading following a  
power-law decay with index alpha=-1.4 (+0.2/-0.1).

The spectrum for the first data sequence, corresponding to a 1.96 ks  
exposure and covering times from T+17 ks to T+23 ks can be fit by a  
power-law with photon index 2.1+/-0.2, with an absorbing column of  
(7.4+/-0.2)E20 cm**-2, in excess with respect to the galactic value  
of 1.94E20 cm**-2 (Kalberla et al. 2005). The observed (unabsorbed)  
flux is 1.7 (2.2)E-11 erg cm**-2 s**-1. The count-rate-to-flux  
conversion factor is (4.3+/-0.1)E-11.

All quoted errors are at 90% confidence level.

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