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GCN Circular 14635

Subject
GRB 130513A: Swift-XRT detection of the afterglow.
Date
2013-05-14T08:42:09Z (11 years ago)
From
Phil Evans at U of Leicester <pae9@leicester.ac.uk>
P.A. Evans (U. Leicester) and F. E. Marshall (NASA/GSFC) report on
behalf of the Swift-XRT team:

We have analysed 3.9 ks of XRT data for the INTEGRAL-detected burst:
GRB 130513A (Mereghetti et al., GCN 14630), from 25.4 ks to 37.2 ks
after the  INTEGRAL trigger. The data are entirely in Photon Counting
(PC) mode.  An X-ray source is detected within the INTEGRAL error
circle. Using 2486 s of PC mode data and 2 UVOT images, we find an
enhanced XRT position (using the XRT-UVOT alignment and matching UVOT
field sources to the USNO-B1 catalogue): RA, Dec = 144.76167, -5.24171
which is equivalent to:

RA (J2000): 09h 39m 02.80s
Dec(J2000): -05d 14' 30.1"

with an uncertainty of 2.7 arcsec (radius, 90% confidence). This
position is 49 arcsec from the INTEGRAL position.  

The source is fading, and the light curve can be modelled with a
power-law of index 3.3 (+1.1, -0.45). We therefore conclude that it is
the afterglow of the GRB.

We detect only 24 photons from this source, so the spectrum is poorly
constrained. The photon index is 2.9 (+2.1, -1.1); the absorption is
consistent with the Galactic value of 3.4e20 cm^-2 (Kalberla et al.
2005) however within the errors on the spectral fit, could be as high
as 5e21 cm^-2.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00020274.

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