TITLE:   GCN CIRCULAR
NUMBER:  26884
SUBJECT: GRB 200125A: Swift-XRT refined Analysis
DATE:    20/01/26 11:44:06 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

A. Tohuvavohu (U. Toronto), J.A. Kennea (PSU), J.P. Osborne (U.
Leicester), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), A.
Melandri (INAF-OAB), P. D'Avanzo (INAF-OAB), M.G. Bernardini
(INAF-OAB), B. Sbarufatti (PSU) and A.Y. Lien report on behalf of the
Swift-XRT team:

We have analysed 5.7 ks of XRT data for GRB 200125A (Lien et al. GCN
Circ. 26876), from 127 s to 28.1 ks after the  BAT trigger. The data
comprise 286 s in Windowed Timing (WT) mode with the remainder in
Photon Counting (PC) mode. The enhanced XRT position for this burst was
given by Beardmore et al. (GCN Circ. 26878). a rise, withpower-law
index .

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index	of 1.523 (+/-0.029). The
best-fitting absorption column is  3.05 (+0.17, -0.16) x 10^21 cm^-2,
in excess of the Galactic value of 7.7 x 10^20 cm^-2 (Willingale et al.
2013). The PC mode spectrum has a photon index of 2.17 (+0.19, -0.18)
and a best-fitting absorption column of 1.3 (+0.5, -0.4) x 10^21 cm^-2.
The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum  is 3.1 x 10^-11 (4.2 x 10^-11) erg cm^-2
count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:	     1.3 (+0.5, -0.4) x 10^21 cm^-2
Galactic foreground: 7.7 x 10^20 cm^-2
Excess significance: 2.0 sigma
Photon index:	     2.17 (+0.19, -0.18)

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00952164.

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