[vsnet-grb-info 27704] GRB 210411C: Swift-XRT refined Analysis

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  29807
SUBJECT: GRB 210411C: Swift-XRT refined Analysis
DATE:    21/04/12 15:33:49 GMT
FROM:    Phil Evans at U of Leicester  <pae9 at leicester.ac.uk>

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

We have analysed 6.4 ks of XRT data for GRB 210411C (Sbarrato et al.
GCN Circ. 29794), from 66 s to 42.0 ks after the  BAT trigger. The data
comprise 136 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. 29800).

The late-time light curve (from T0+5.4 ks) can be modelled with a
power-law decay with a decay index of alpha=1.49 (+/-0.17).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index	of 2.66 (+0.19, -0.18). The
best-fitting absorption column is  1.2 (+0.4, -0.3) x 10^21 cm^-2, in
excess of the Galactic value of 8.1 x 10^20 cm^-2 (Willingale et al.
2013). The PC mode spectrum has a photon index of 1.84 (+0.14, -0.11)
and a best-fitting absorption column of 9.4 (+4.0, -1.3) x 10^20 cm^-2.
The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum  is 3.6 x 10^-11 (4.3 x 10^-11) erg cm^-2
count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:	     9.4 (+4.0, -1.3) x 10^20 cm^-2
Galactic foreground: 8.1 x 10^20 cm^-2
Excess significance: <1.6 sigma
Photon index:	     1.84 (+0.14, -0.11)

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/01042398.

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