[vsnet-grb-info 23995] GRB 191029A: Swift-XRT refined Analysis

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  26094
SUBJECT: GRB 191029A: Swift-XRT refined Analysis
DATE:    19/10/29 22:49:41 GMT
FROM:    Phil Evans at U of Leicester  <pae9 at leicester.ac.uk>

P. D'Avanzo (INAF-OAB), J.A. Kennea (PSU), B. Sbarufatti (PSU), D.N.
Burrows (PSU), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester),
M.G. Bernardini (INAF-OAB), E. Ambrosi	(INAF-IASFPA)  and P.A. Evans
report on behalf of the Swift-XRT team:

We have analysed 9.0 ks of XRT data for GRB 191029A (Evans et al. GCN
Circ. 26088), from 4.0 ks to 27.7 ks after the	BAT trigger. The data
are entirely in Photon Counting (PC) mode. The refined XRT position is
RA, Dec = 352.1492, -40.5661 which is equivalent to:

RA (J2000): 23 28 35.80
Dec(J2000): -40 33 58.0

with an uncertainty of 3.6 arcsec (radius, 90% confidence). The light
curve is consistent with a constant source of mean count rate 8.2e-02
ct/sec. A power-law fit gives an index of 0.08 (+0.12, -0.13).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.54 (+0.16, -0.10). The
best-fitting absorption column is  1.92 (+3.90, -0.14) x 10^20 cm^-2,
consistent with the Galactic value of 1.8 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 3.9 x 10^-11 (4.0 x
10^-11) erg cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:	     1.92 (+3.90, -0.14) x 10^20 cm^-2
Galactic foreground: 1.8 x 10^20 cm^-2
Excess significance: <1.6 sigma
Photon index:	     1.54 (+0.16, -0.10)

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00932058.

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