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GCN Circular 15845

Subject
GRB 140215A: Swift-XRT refined Analysis
Date
2014-02-15T16:18:01Z (10 years ago)
From
Kim Page at U.of Leicester <klp5@leicester.ac.uk>
K.L. Page (U. Leicester) and C. B. Markwardt (NASA/GSFC) report on
behalf of the Swift-XRT team:

We have analysed 7.8 ks of XRT data for GRB 140215A (Markwardt	et al.
GCN Circ. 15837),  from 124 s to 18.2 ks after the BAT trigger. The
data comprise 159 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. 15842).

The light curve can be modelled with  a power-law decay with a decay
index of alpha=1.21 (+/-0.03).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index	of 1.49 (+0.12, -0.07). The
best-fitting absorption column is  consistent with the Galactic value
of 9.7 x 10^20 cm^-2 (Kalberla et al. 2005). The PC mode spectrum has a
photon index of 1.91 (+0.18, -0.17) and a best-fitting absorption
column of 1.7 (+/-0.5) x 10^21 cm^-2. The counts to observed
(unabsorbed) 0.3-10 keV flux conversion factor deduced from this
spectrum  is 4.0 x 10^-11 (5.4 x 10^-11) erg cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:	     1.7 (+/-0.5) x 10^21 cm^-2
Galactic foreground: 9.7 x 10^20 cm^-2
Excess significance: 2.5 sigma
Photon index:	     1.91 (+0.18, -0.17)

If the light curve continues to decay with a power-law decay index of
1.21, the count rate at T+24 hours will be 5.1 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 2.0 x
10^-13 (2.8 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/00586680.

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