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GCN Circular 5966

Subject
GRB 061222A: Swift-XRT refined analysis
Date
2006-12-22T07:11:40Z (17 years ago)
From
Dirk Grupe at PSU/Swift-XRT <grupe@astro.psu.edu>
D. Grupe (PSU) reports on behalf of the Swift/XRT team



We have analyzed the first orbit of GRB 061222A (Grupe et al., GCN 5954)
with total observing times of 117s in Windowed Timing mode and
1476s in Photon Counting mode in the Swift XRT. The Photon Counting mode 
image
provides a refined XRT position at RA, Dec= 358.263708, +46.53297, which is

RA(J2000) = 23h 53m 03.29s
Dec(J2000) = +46d 31' 58.7"

with an error of 3.5" (90% confidence). This position is 2.4"
away from the preliminary XRT position reported in GCN 5954.

The X-ray light curve displays the end of a flare as seen in the BAT (at 
the beginning of the
XRT observation this flare had an initial count rate of about 100 
counts/s) and decays
with a slope of 0.26+/-0.03.

Spectral fits to the Windowed Timing mode data show an
absorption column density  significantly in excess of the Galactic value 
(1.01e21 cm**-2)
with an excess absorption column density of (3.7+/-0.3)e21 cm**-2 and a 
energy spectral
slope beta-x=1.34+/-0.08. Following the relation given in Grupe et al. 
2006 (AJ submitted,
astro-ph/0612104) the high excess absorption column density suggests 
that this
burst is at a redshift z<3.0.

Even though the observations were shortly interrupted by a new burst, 
GRB 06122B
(Racusin et al., GCN 5957), we continue observing GRB 061222A with Swift
throughout the next hours. More analysis of the data will be presented 
in the
GCN report.

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