[vsnet-grb-info 10756] GRB 110719A: Swift-XRT refined Analysis

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  12178
SUBJECT: GRB 110719A: Swift-XRT refined Analysis
DATE:    11/07/19 15:57:30 GMT
FROM:    Claudio Pagani at U of Leicester  <cp232 at star.le.ac.uk>

C. Pagani (U. Leicester) and T. Sakamoto (NASA/UMBC) report on behalf
of the Swift-XRT team:

We have analysed 4.5 ks of XRT data for GRB 110719A (Sakamoto  et al.
GCN Circ. 12173), from 117 s to 12.1 ks after the  BAT trigger. The
data comprise 258 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 12176).

The light curve can be modelled with a series of power-law decays. The
initial decay index is alpha=0.59 (+0.26, -0.30). At T+219 s  the decay
steepens to an alpha of 2.6 (+/-0.4) before breaking again at T+1393 s
to a final decay with index alpha=0.7 (+0.7, -0.6).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index	of 1.39 (+0.13, -0.12). The
best-fitting absorption column is  9.0 (+3.8, -3.4) x 10^20 cm^-2, in
excess of the Galactic value of 4.0 x 10^20 cm^-2 (Kalberla et al.
2005). The PC mode spectrum has a photon index of 1.58 (+0.26, -0.15)
and a best-fitting absorption column consistent with the Galactic
value. The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum  is 4.6 x 10^-11 (4.9 x 10^-11) erg
cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:	     4.0 (+5.9, -0) x 10^20 cm^-2
Galactic foreground: 4.0 x 10^20 cm^-2
Excess significance: <1.6 sigma
Photon index:	     1.58 (+0.26, -0.15)

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00457553.

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