TITLE:   GCN CIRCULAR
NUMBER:  29014
SUBJECT: GRB 201209A: Swift-XRT refined Analysis
DATE:    20/12/09 15:38:51 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

J. D. Gropp (PSU), J.A. Kennea (PSU), A. Tohuvavohu (U. Toronto), A.P.
Beardmore (U. Leicester), P.A. Evans (U. Leicester), J.P. Osborne (U.
Leicester), A. Melandri (INAF-OAB), T. Sbarrato (INAF-OAB), P. D'Avanzo
(INAF-OAB) and J.D. Gropp report on behalf of the Swift-XRT team:

We have analysed 6.2 ks of XRT data for GRB 201209A (Gropp et al. GCN
Circ. 29005), from 117 s to 29.1 ks after the  BAT trigger. The data
comprise 43 s in Windowed Timing (WT) mode with the remainder in Photon
Counting (PC) mode. The enhanced XRT position for this burst was given
by Goad et al. (GCN Circ. 29009).A spectrum formed from the PC mode
data can be fitted with an absorbed power-law with a photon spectral
index of 1.98 (+/-0.08). The best-fitting absorption column is	1.54
(+0.26, -0.25) x 10^21 cm^-2, in excess of the Galactic value of 3.6 x
10^20 cm^-2 (Willingale et al. 2013). The counts to observed
(unabsorbed) 0.3-10 keV flux conversion factor deduced from this
spectrum  is 3.5 x 10^-11 (4.3 x 10^-11) erg cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:	     1.54 (+0.26, -0.25) x 10^21 cm^-2
Galactic foreground: 3.6 x 10^20 cm^-2
Excess significance: 7.9 sigma
Photon index:	     1.98 (+/-0.08)

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/01011980.

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