[vsnet-grb-info 3881] RB 061007: Swift XRT refined analysis

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  5712
SUBJECT: RB 061007: Swift XRT refined analysis
DATE:    06/10/07 21:21:39 GMT
FROM:    Loredana Vetere at PSU  <vetere at astro.psu.edu>

L. Vetere, C. Pagani, D. N. Burrows (PSU) and P. Schady (MSSL-UCL) report on
behalf of the Swift XRT team:

We have analysed the first 3 orbits of XRT data from GRB 061007. This is one of
the brightest GRB afterglow ever observed by XRT.
A 5.2ks photon counting mode image provides a refined XRT position:

RA(J2000)  =  03 05 19.1
Dec(J2000) = -50 30 01.5

with an uncertainty of 5 arcsec (90% containment). This position is 3.8 arcsec
away from the on-board XRT position and 4 arcsec away from UVOT position
(Schady et al. GCN 5707).

The X-ray light curve shows a rapid decay with a slope of -1.6 +/-0.1. A
power-law fit to the WT spectrum gives a photon index of  2.36 +/- 0.2 and a
column density of (2.2 +/- 0.2)e21 cm**-2. We note the galactic hydrogen column
density in the direction of the burst is  2.13e20cm**-2. The 0.2-10.0 keV
observed mean flux during WT observation is 1.46e-07 ergs cm**-2 s**-1, which
corresponds to an unabsorbed flux of 2.98e-07 ergs cm**-2 s**-1.

If the burst continues decaying at the current rate we estimate an XRT
count rate of 0.0069 counts/s at T + 24hr, which corresponds to an
observed 0.2-10.keV flux of 5.7e-11 ergs cm**-2 s**-1.

This circular is an official product of the Swift XRT Team.