[vsnet-grb-info 10231] GRB 110208A: Swift-XRT refined Analysis

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  11679
SUBJECT: GRB 110208A: Swift-XRT refined Analysis
DATE:    11/02/09 14:42:48 GMT
FROM:    Valerio D'Elia at ASDC  <delia at asdc.asi.it>

V. D'Elia (ASDC) reports on behalf of the Swift-XRT team:

We have analysed 20 ks of XRT data for GRB 110208A (D'Elia  et al. GCN
Circ. 11674), from 64 s to 47.3 ks after the  BAT trigger. The data
comprise 55 s in Windowed Timing (WT) mode (the first 9 s were taken
while Swift was slewing) with the remainder in Photon Counting (PC)
mode. The enhanced XRT position for this burst was given by Evans et
al. (GCN. Circ 11678).

The late-time light curve (from T0+4.3 ks) can be modelled with  a
power-law decay with a decay index of alpha=1.21 (+0.20, -0.18).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.27 (+/-0.25). The
best-fitting absorption column is  1.1 (+0.4, -0.6) x 10^21 cm^-2, in
excess of the Galactic value of 2.3 x 10^20 cm^-2 (Kalberla et al.
2005). The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum  is 3.3 x 10^-11 (4.7 x 10^-11) erg
cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:	     1.1 (+0.4, -0.6) x 10^21 cm^-2
Galactic foreground: 2.3 x 10^20 cm^-2
Excess significance: 3.2 sigma
Photon index:	     2.27 (+/-0.25)

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00445038.

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