GCN Circular 4462
Subject
GRB 060109: Refined Swift-XRT analysis
Date
2006-01-10T08:15:16Z (18 years ago)
From
Kim Page at U.of Leicester <kpa@star.le.ac.uk>
A.P. Beardmore, K.L. Page (U.Leicester), J. Kennea (PSU), M. De Pasquale
(UCL-MSSL), P. Meszaros, M. Chester (PSU) report on behalf of the Swift
XRT team:
We have analysed the first four orbits of Swift-XRT data from GRB 060109.
8.3ks of PC mode data give a refined position of
RA(J2000) = 18h 50m 43.5s
Dec(J2000) = +31d 59' 29.7"
with an estimated uncertainty of 3.2 arcsec (90% containment). This
position is 7.7 arcsec away from the on-board XRT position quoted in De
Pasquale et al. (GCN 4455) and includes the latest XRT boresight
correction.
The X-ray lightcurve shows a steeply declining early phase, with a decay
slope of 5.1, which breaks to a shallower slope of 0.14 at about 300s.
This is followed by a second break at 6100s to a slope of 1.2.
The X-ray spectrum 100s to 200s after the BAT trigger can be fitted with
an absorbed power-law with a photon index of 1.85+/-0.09 and a column
density consistent with the Galactic value in this direction of 1.0e21
cm**2. The observed (unabsorbed) 0.3-10.0 keV flux over this interval is
5.1E-10 (6.2E-10) ergs cm**-2 s**-1.
If the source continues to fade at the current rate we predict an XRT
count rate of 0.006 counts/s 24hrs after the trigger, which corresponds
to an observed (0.3-10 keV) flux of 2.4e-11 ergs cm**-2 s**-1.