[vsnet-grb-info 2814] GRB060203: Swift XRT Team Refined Analysis

[GCN Circulars]

TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  4651
SUBJECT: GRB060203: Swift XRT Team Refined Analysis
DATE:    06/02/04 07:33:49 GMT
FROM:    David Morris at PSU/Swift-XRT  <morris at astro.psu.edu>

D. Morris (PSU), D. Burrows (PSU), N. Gehrels (GSFC), P. Boyd 
(GSFC-UMBC), W. Voges (MPE) report on behalf of the Swift XRT team:

We have analyzed the Swift XRT data from the first two orbits of GRB 
060203 (Retter et al., GCN4641), with a total exposure of 5000 seconds. 
The refined XRT position is:

RA(J2000) = 06h 54m 04.35s
Dec(J2000) = +71d 48' 38.4"

This position is 44.6 arcseconds from the BAT position, 2.5 arcseconds 
from the XRT position given in GCN4644 and 2.4 arcseconds from the 
optical counterpart position given in GCN4645 (Malesani et al). We 
estimate an uncertainty of 4 arcseconds radius (90% containment).

The 0.2-10 keV light curve in Photon Counting (PC) mode starts 3100 
seconds from the BAT trigger (T0).  The lightcurve shows evidence of a 
shallow decay index of 0.6.

A preliminary spectral fit to the PC data gives a spectral power law 
photon index of 2.24 ± 0.3 in the 0.2-10 keV band with NH of 1.9e21 ± 
7e20, above the galactic NH value for this direction of 6e20. The 
unabsorbed 0.2-10 keV flux at the start of the XRT observation is 
estimated to be about 1E-11 erg/cm2/s. If the current decay slope 
continues, we predict an unabsorbed 0.2-10 keV flux of about 1e-12 
erg/cm2/s at T+24hrs.