GCN 43492: GRB 260120B: Swift-XRT refined Analysis

M. Ferro (INAF-OAB), R. Brivio (INAF-OAB), A. D'Ai (INAF-IASFPA), S.
Lanava (PSU), S. Dichiara (PSU), J.A. Kennea (PSU), J.P. Osborne (U.
Leicester), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester) and
P.A. Evans report on behalf of the Swift-XRT team:

We have analysed 5.6 ks of XRT data for GRB 260120B, from 130 s to 29.5
ks after the   trigger. The data comprise 13 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 light curve can be modelled with a power-law decay with a decay
index of alpha=0.84 (+/-0.06).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.97 (+0.29, -0.27). The
best-fitting absorption column is  2.1 (+1.2, -1.0) x 10^21 cm^-2, in
excess of the Galactic value of 7.4 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 3.7 x 10^-11 (5.1 x 10^-11) erg
cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:	     2.1 (+1.2, -1.0) x 10^21 cm^-2
Galactic foreground: 7.4 x 10^20 cm^-2
Excess significance: 2.4 sigma
Photon index:	     1.97 (+0.29, -0.27)

The results of the XRT-team automatic analysis are available at
https://www.swift.ac.uk/xrt_products/01442454.

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