GCN Circular 13687
Subject
GRB 120819A: Swift-XRT refined Analysis
Date
2012-08-20T05:47:04Z (12 years ago)
From
Phil Evans at U of Leicester <pae9@star.le.ac.uk>
O.M. Littlejohns (U. Leicester), V. D'Elia (ASDC), A. Maselli
(INAF-IASFPA), V. Mangano (INAF-IASFPA), D.N. Burrows (PSU), J.A.
Kennea (PSU), M.C. Stroh (PSU), J.P. Osborne (U. Leicester), K.L. Page
(U. Leicester) and A.P. Beardmore report on behalf of the Swift-XRT
team:
We have analysed 10 ks of XRT data for GRB 120819A (Beardmore et al.
GCN Circ. 13681), from 159 s to 23.0 ks after the BAT trigger. The
data comprise 67 s in Windowed Timing (WT) mode with the remainder in
Photon Counting (PC) mode. The enhanced XRT position for this burst was
given by Evans et al. (GCN. Circ 13684).
The light curve can be modelled with a power-law decay with a decay
index of alpha=1.75 (+0.12, -0.09).
A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.7 (+/-0.4). The
best-fitting absorption column is 3.3 (+2.0, -1.5) x 10^21 cm^-2, in
excess of the Galactic value of 8.9 x 10^20 cm^-2 (Kalberla et al.
2005). The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum is 4.2 x 10^-11 (6.0 x 10^-11) erg
cm^-2 count^-1.
A summary of the WT-mode spectrum is thus:
Total column: 3.3 (+2.0, -1.5) x 10^21 cm^-2
Galactic foreground: 8.9 x 10^20 cm^-2
Excess significance: 2.6 sigma
Photon index: 1.7 (+/-0.4)
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00531428.
This circular is an official product of the Swift-XRT team.