GCN Circular 4481

Subject

GRB060111 : XRT refined analysis

Event

Date

2006-01-11T13:23:02Z (20 years ago)

From

Michael Goad at U Leicester <mrg@star.le.ac.uk>

M.R. Goad, A.P. Beardmore, K. Page (U. Leicester), D. Burrows (PSU), R. Fink
(GSFC), M. Ajello (MPE) report on behalf of the Swift XRT team.

From analysis of 2.5 ks of Photon Counting mode data of GRB060111 (Zane et
al., GCN 4479Loading...
 
 ) starting in the 2nd orbit of observations, we obtain a refined
XRT position of RA: 18h 24m 49.0s, Dec:+37d 36m 16.1s (J2000) with an
uncertainty of 3.6 arcsec (90% containment). This includes the latest XRT
boresight correction. This refined position is 25.1 arcsec from the BAT
on-board position and 5 arcsec from the XRT on-board position quoted in GCN
4479Loading...
 
 .

We have also analysed 400 s of XRT Windowed Timing mode observations starting
78 s after the BAT trigger. The XRT lightcurve displays 3 large flares with a
peak count rate of approximately 150 ct/s occurring 280 s after the BAT
trigger. The light-curve has an underlying powerlaw decay of slope -1.3.

The XRT WT mode 0.3-10 keV spectrum is well represented by an absorbed
powerlaw with photon index 2.35 +/-0.04 with a mean unabsorbed flux of 2.5e-9
ergs/cm2/s. We find evidence for excess NH of 2.4e21 cm^-2.

The predicted 0.3-10 keV unabsorbed flux 24 hours after the BAT trigger is
1.2e-13 ergs/cm2/s