[vsnet-grb-info 24091] GRB 191106A: Swift-XRT refined Analysis

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  26190
SUBJECT: GRB 191106A: Swift-XRT refined Analysis
DATE:    19/11/06 21:28:30 GMT
FROM:    Phil Evans at U of Leicester  <pae9 at leicester.ac.uk>

K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), P.A. Evans (U.
Leicester), M. Perri (ASDC), V. D'Elia (ASDC), A. D'Ai (INAF-IASFPA),
A. Tohuvavohu (U. Toronto), J.A. Kennea (PSU), B. Sbarufatti (PSU) and
F.E. Marshall report on behalf of the Swift-XRT team:

We have analysed 6.3 ks of XRT data for GRB 191106A (Marshall et al.
GCN Circ. 26177), from 106 s to 13.2 ks after the  BAT trigger. The
data are entirely in Photon Counting (PC) mode. The best available XRT
position  (using the promptly downlinked event data, the XRT-UVOT
alignment and matching UVOT field sources to the USNO-B1 catalogue) is
RA, Dec = 269.3356, 46.0353 which is equivalent to:

RA (J2000): 17 57 20.55
Dec(J2000): +46 02 06.9

with an uncertainty of 2.3 arcsec (radius, 90% confidence).

The light curve can be modelled with a power-law decay with a decay
index of alpha=3.37 (+0.33, -0.30).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.1 (+/-0.6). The
best-fitting absorption column is  3.1 (+3.1, -2.1) x 10^21 cm^-2, in
excess of the Galactic value of 4.4 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 (5.6 x 10^-11) erg
cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:	     3.1 (+3.1, -2.1) x 10^21 cm^-2
Galactic foreground: 4.4 x 10^20 cm^-2
Excess significance: 2.1 sigma
Photon index:	     2.1 (+/-0.6)

If the light curve continues to decay with a power-law decay index of
3.37, the count rate at T+24 hours will be 7.4 x 10^-10 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 2.7 x
10^-20 (4.1 x 10^-20) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00933515.

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