[vsnet-grb-info 4083] GRB 061202: Swift XRT refined analysis

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  5893
SUBJECT: GRB 061202: Swift XRT refined analysis
DATE:    06/12/02 19:25:20 GMT
FROM:    Giulia Stratta at ASDC  <stratta at asdc.asi.it>

G. Stratta, M. Perri, M.L. Conciatore (ASDC), D. N. Burrows (PSU) and
T. Sakamoto (NASA/ORAU) report on behalf of the Swift XRT team:

We have analysed the first five orbits of Swift XRT data on the BAT GRB
061202 (Sakamoto, et al., GCN Circ. 5886; Sakamoto et al., GCN Circ.
5887).
A 7.6ks photon counting mode image provides a refined XRT position:

RA(J2000) = 07h 02m 05.55s
Dec(J2000) = -74d 41m 54.6"

with an uncertainty of 3.5" (90% containment). This is 8.6' away from
the centre of the refined BAT position quoted in GCN Circ. 5887 (Sakamoto
et al.), and 4.0" away from the initial XRT position quoted in
GCN Circ. 5886 (Sakamoto et al.).

The early X-ray light curve displays a large flare peaking at a count rate
of approximately 115 counts/s at T+140s followed by a shallow phase up to
about T+13ks. At later times the afterglow curve shows a decline with a
power-law decay with index alpha=-1.6+/-0.4.

The X-ray spectrum covering the time period from T+126s to T+310s is well
fit by an absorbed power-law with a photon index of 1.9+/-0.1 and column
density of (6.0+/-0.5)e21 cm**-2 (errors are at 90% confidence level).
We note the Galactic column density in the direction of the source is
1.16e21 cm**-2. The observed (unabsorbed) 0.3-10 keV flux for this
spectrum is 1.5e-09 (2.5e-09) erg/cm**2/s.

Assuming the X-ray emission continues to decline at the same rate, we
predict a 0.3-10 keV XRT count rate of 0.02 count/s at T+24hr, which
corresponds to an observed (unabsorbed) 0.3-10 keV flux of
1.2e-12 (2.0e-12) erg/cm**2/s.

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