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GCN Circular 14198

Subject
GRB 130211A: Swift-XRT refined Analysis
Date
2013-02-11T18:58:03Z (11 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
D.N. Burrows (PSU), O.M. Littlejohns (U. Leicester), J.P. Osborne (U.
Leicester), K.L. Page (U. Leicester), A. Melandri (INAF-OAB), B.
Sbarufatti (INAF-OAB/PSU), G. Stratta (ASDC), J.A. Kennea (PSU), M.C.
Stroh (PSU) and S.R. Oates report on behalf of the Swift-XRT team:

We have analysed 9.2 ks of XRT data for GRB 130211A (Oates  et al. GCN
Circ. 14195),  from 120 s to 29.1 ks after the	BAT trigger. The data
comprise 201 s in Windowed Timing (WT) mode with the remainder in
Photon Counting (PC) mode. The refined XRT position is RA, Dec =
147.53616, -42.34237 which is equivalent to:

RA (J2000): 09 50 08.68
Dec(J2000): -42 20 32.5

with an uncertainty of 3.6 arcsec (radius, 90% confidence).

The light curve can be modelled with  a power-law decay with a decay
index of alpha=2.85 (+0.27, -0.23).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index	of 3.55 (+/-0.14). The
best-fitting absorption column is  5.9 (+/-0.4) x 10^21 cm^-2, in
excess of the Galactic value of 2.2 x 10^21 cm^-2 (Kalberla et al.
2005). The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum  is 2.5 x 10^-11 (2.3 x 10^-10) erg
cm^-2 count^-1. 

A summary of the WT-mode spectrum is thus:
Total column:	     5.9 (+/-0.4) x 10^21 cm^-2
Galactic foreground: 2.2 x 10^21 cm^-2
Excess significance: 15.9 sigma
Photon index:	     3.55 (+/-0.14)

If the light curve continues to decay with a power-law decay index of
2.85, the count rate at T+24 hours will be 1.3 x 10^-7 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 3.3 x
10^-18 (3.1 x 10^-17) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00548276.

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