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GCN Circular 15739

Subject
GRB 140114A: Swift-XRT refined Analysis
Date
2014-01-15T00:23:05Z (10 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
V. Mangano (PSU), M.C. Stroh (PSU), P.A. Evans (U. Leicester), B.P.
Gompertz (U. Leicester), J.P. Osborne (U. Leicester), B. Sbarufatti
(INAF-OAB/PSU), P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), D.N. Burrows
(PSU) and E. Troja report on behalf of the Swift-XRT team:

We have analysed 11 ks of XRT data for GRB 140114A (Troja  et al. GCN
Circ. 15728),  from 118 s to 24.7 ks after the	BAT trigger. The data
comprise 449 s in Windowed Timing (WT) mode with the remainder in
Photon Counting (PC) mode. The enhanced XRT position for this burst was
given by Beardmore et al. (GCN. Circ 15733).

The late-time light curve (from T0+5.0 ks) can be modelled with  a
power-law decay with a decay index of alpha=0.50 (+/-0.15).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index	of 2.22 (+/-0.03). The
best-fitting absorption column is  1.53 (+/-0.07) x 10^21 cm^-2, in
excess of the Galactic value of 1.6 x 10^20 cm^-2 (Kalberla et al.
2005). The PC mode spectrum has a photon index of 2.33 (+0.21, -0.20)
and a best-fitting absorption column of 1.3 (+0.5, -0.4) x 10^21 cm^-2.
The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum  is 3.1 x 10^-11 (4.8 x 10^-11) erg cm^-2
count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:	     1.3 (+0.5, -0.4) x 10^21 cm^-2
Galactic foreground: 1.6 x 10^20 cm^-2
Excess significance: 4.5 sigma
Photon index:	     2.33 (+0.21, -0.20)

If the light curve continues to decay with a power-law decay index of
0.50, the count rate at T+24 hours will be 0.020 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 6.2 x
10^-13 (9.6 x 10^-13) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00583861.

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