[vsnet-grb-info 2832] GRB060204B: Swift XRT Team Refined Analysis

[GCN Circulars]

TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  4669
SUBJECT: GRB060204B: Swift XRT Team Refined Analysis
DATE:    06/02/05 03:44:58 GMT
FROM:    Abe Falcone at PSU/Swift  <afalcone at astro.psu.edu>

A. D. Falcone (PSU), D. N. Burrows (PSU), D. C. Morris (PSU), N. Gehrels 
(GSFC) report on behalf of the Swift XRT team:

We have analyzed the initial Swift XRT data from GRB 060204B (Falcone et
al., GCN4655), with a total exposure of 178 s in Windowed Timing mode 
and 7790 s in Photon Counting mode.
The refined XRT position is:

RA(J2000) = 14 07 14.8
Dec(J2000) = +27 40 34

This position is 3" from the initial XRT on-board centroiding position
reported in GCN 4655, and it is 2.8" from the optical detection reported
by Guidorzi et. al (GCN 4661).  We estimate an uncertainty of 4
arcseconds radius (90% containment).

The early light curve is dominated by flaring with rates reaching
approximately 200 c/s.  Following the initial flaring, the light curve
is clearly fading, but the rate is difficult to estimate due to the
flaring and the limited data available at this time.  A preliminary
estimate of the power law decay index is approximately 0.6 +/- 0.4,
immediately following the flaring activity.  There is some indication
that the lightcurve may become steeper beyond approximately 10 ks.

Based on a preliminary spectral fit to the PC data in the time region
between 200-5000 seconds, the spectrum can be described by an absorbed
power law, with a power law photon index of 1.9 +/- 0.2 and N_H of 10e20
+/- 5e20 cm^-2.  The 0.2-10 keV flux during this time frame is estimated
to be approximately 4e-12 erg/cm^2/s.

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