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GCN Circular 5703

GRB 061006: Swift-XRT Team Refined Analysis
2006-10-07T02:24:20Z (18 years ago)
Eleonora Troja at INAF-IASFPA <>
E. Troja (U. Leicester/INAF-IASFPa), K. L. Page(U. Leicester), 
D. N. Burrows (PSU) & P. Schady (MSSL-UCL) report on behalf of the Swift-XRT 

We have analysed the first 4 orbits of Swift-XRT data obtained for GRB 061006 
(GCN Circ. 5699; Schady et al.). Our data set consists of 7.8 ks in Photon
Counting (PC) mode.

We derived a XRT refined position of:

RA(J2000) = 07h 24m 06.36s 
Dec(J2000) = -79d 11' 56.80''

with an estimated error radius of 6 arcsec (90% containment, including 
boresight uncertainties). This lies 2.3 arcsec from the preliminary XRT 
position and 45'' arcsec from the on-board calculated BAT position, reported 
in GCN 5699.

The X-ray lightcurve shows an initial slope of 2.26 +/- 0.10, breaking around 
290 s after the burst to a flatter decay slope of 0.77 +/- 0.07. 

The time-averaged spectrum (from T+155 s to T+18.6 ks) can be fit with an 
absorbed power-law with a photon index of 1.7 +/- 0.4 and an absorption 
column of 1.8e21 cm^-2, consistent at the 90% confidence level with the 
Galactic value in the direction of the burst (1.33e21 cm^-2).
The mean observed (unabsorbed) flux in the 0.2-10 keV energy band is 1.4e-12 
(1.9e-12) erg cm^-2 s^-1.

If the afterglow continues decaying at the same rate, the count rate at T+24 h 
is predicted to be 1.8e-3 cts s^-1, corresponding to an unabsorbed 0.2-10 keV 
flux of 1.5e-13 erg cm^-2 s^-1.

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