[vsnet-grb-info 11832] GRB 120403B: Swift-XRT refined Analysis

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  13223
SUBJECT: GRB 120403B: Swift-XRT refined Analysis
DATE:    12/04/05 09:05:05 GMT
FROM:    Phil Evans at U of Leicester  <pae9 at star.le.ac.uk>

O.M. Littlejohns (U. Leicester), A. Melandri (INAF-OAB), B. Sbarufatti
(INAF-OAB/PSU), G. Stratta (ASDC), D.N. Burrows (PSU), J.A. Kennea
(PSU), M.C. Stroh (PSU), J.P. Osborne (U. Leicester), K.L. Page (U.
Leicester) and V.D'Elia report on behalf of the Swift-XRT team:

We have analysed 4.5 ks of XRT data for GRB 120403B (D'Elia  et al. GCN
Circ. 13203), from 920 s to 8.9 ks after the  BAT trigger. The data are
entirely in Photon Counting (PC) mode. The enhanced XRT position for
this burst was given by Goad et al. (GCN. Circ 13205).

The light curve can be modelled with  a power-law decay with a decay
index of alpha=0.80 (+0.15, -0.14).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.2 (+/-0.3). The
best-fitting absorption column is  2.2 (+0.9, -0.8) x 10^21 cm^-2, in
excess of the Galactic value of 9.5 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 3.5 x 10^-11 (5.8 x 10^-11) erg
cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:	     2.2 (+0.9, -0.8) x 10^21 cm^-2
Galactic foreground: 9.5 x 10^20 cm^-2
Excess significance: 2.5 sigma
Photon index:	     2.2 (+/-0.3)

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00519256.

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