[vsnet-grb-info 15636] GRB 141015A: Swift-XRT afterglow confirmation and refined Analysis

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  16925
SUBJECT: GRB 141015A: Swift-XRT afterglow confirmation and refined Analysis
DATE:    14/10/19 08:10:41 GMT
FROM:    Phil Evans at U of Leicester  <pae9 at leicester.ac.uk>

E. Troja (NASA/GSFC/UMCP) reports on behalf of the Swift-XRT team:

We have analysed 9.0 ks of XRT data for GRB 141015A (Troja  et al. GCN
Circ. 16909),  from 21.3 ks to 271.2 ks after the  BAT trigger. The
data are entirely in Photon Counting (PC) mode. The enhanced XRT
position for this burst was given by Evans et al. (GCN Circ. 16913). 

The GRB light curve in the initial observation was at a level of ~0.02
ct/sec in XRT. In subsequent observations the GRB is undetected, with
an upper limit of 0.004 ct/sec, we therefore confirm that this was the
afterglow of GRB 141015A.
 
A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.38 (+0.51, -0.20). The
best-fitting absorption column is  consistent with the Galactic value
of 5.6 x 10^21 cm^-2 (Willingale et al. 2013). The counts to observed
(unabsorbed) 0.3-10 keV flux conversion factor deduced from this
spectrum  is 6.0 x 10^-11 (7.5 x 10^-11) erg cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:	     5.6 (+/-3.8) x 10^21 cm^-2
Galactic foreground: 5.6 x 10^21 cm^-2
Excess significance: <1.6 sigma
Photon index:	     1.38 (+0.51, -0.20)

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00615399.

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