[vsnet-grb-info 11563] GRB 120215A: Swift-XRT refined Analysis

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  12959
SUBJECT: GRB 120215A: Swift-XRT refined Analysis
DATE:    12/02/15 12:51:03 GMT
FROM:    Phil Evans at U of Leicester  <pae9 at star.le.ac.uk>

M.C. Stroh (PSU), D.N. Burrows (PSU), P.A. Evans (U. Leicester), O.M.
Littlejohns (U. Leicester), J.P. Osborne (U. Leicester), B. Sbarufatti
(INAF-OAB/PSU), G. Stratta (ASDC), P. D'Avanzo (INAF-OAB), J.A. Kennea
(PSU) and E.A. Hoversten report on behalf of the Swift-XRT team:

We have analysed 9.4 ks of XRT data for GRB 120215A (Hoversten	et al.
GCN Circ. 12954), from 110 s to 19.3 ks after the  BAT trigger. The
data comprise 36 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 12957).

The light curve can be modelled with an initial power-law decay with an
index of alpha=3.38 (+0.26, -0.23), followed by a break at T+699 s to
an alpha of -0.28 (+0.15, -0.18).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.10 (+0.24, -0.22). The
best-fitting absorption column is  8.4 (+5.1, -3.0) x 10^20 cm^-2,
consistent with the Galactic value of 5.4 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 3.4 x 10^-11 (4.4 x
10^-11) erg cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:	     8.4 (+5.1, -3.0) x 10^20 cm^-2
Galactic foreground: 5.4 x 10^20 cm^-2
Excess significance: <1.6 sigma
Photon index:	     2.10 (+0.24, -0.22)

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00515015.

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