[vsnet-grb-info 13487] GRB 130606B: Swift-XRT observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  14820
SUBJECT: GRB 130606B: Swift-XRT observations
DATE:    13/06/08 00:26:50 GMT
FROM:    Jamie A. Kennea at PSU/Swift-XRT  <kennea at swift.psu.edu>

J. A. Kennea (PSU)  reports on behalf of the Swift-XRT team:

We have analysed 3.1 ks of XRT data for the Fermi/LAT-detected burst:
GRB 130606B,  from 106.6 ks to 114.1 ks after the  Fermi/LAT trigger.
The data are entirely in Photon Counting (PC) mode.  An X-ray source is
detected within the Fermi/LAT error circle. Using 2899 s of PC mode
data and 4 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 = 218.52931, -22.10229 which is equivalent to:

RA (J2000): 14h 34m 07.04s
Dec(J2000): -22d 06' 08.2"

with an uncertainty of 1.8 arcsec (radius, 90% confidence). This
position is 181 arcsec from the Fermi/LAT position.  the light curve is
consistent with a constant source of mean count rate 8.0e-02 ct/sec. 

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.3 (+/-0.4). The
best-fitting absorption column is  2.0 (+1.0, -0.9) x 10^21 cm^-2, in
excess of the Galactic value of 6.7 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 3.3 x 10^-11 (5.6 x 10^-11) erg
cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:	     2.0 (+1.0, -0.9) x 10^21 cm^-2
Galactic foreground: 6.7 x 10^20 cm^-2
Excess significance: 2.5 sigma
Photon index:	     2.3 (+/-0.4)

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00020283.

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