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GCN Circular 6521

GRB 070612B: Swift-XRT refined analysis
2007-06-12T20:01:19Z (17 years ago)
Dirk Grupe at PSU/Swift-XRT <>
D. Grupe (PSU) reports on behalf of the Swift/XRT team

We have analyzed two orbits of GRB 070612B (Grupe et al., GCN 6509)
with total observing times of 4.7 ks
in Photon Counting mode in the Swift XRT.
Due to Earth-constrain Swift did not slew immediately and XRT 
observations were
delayed by almost one hour (Grupe \& Evans, GCN 6514).
The Photon Counting mode image
provides a refined XRT position at
Ra, Dec= 261.7271, -8.7517, which is

RA(J2000) = 17h 26m 54.49s
Dec(J2000) = -08d 45' 06.3"

with an error of 4.0" (90% confidence). This position is 2.7 "
away from the preliminary XRT position reported in GCN 6514.

The X-ray light curve shows a decaying source. While the afterglow is 
detected in the first orbit, only a 3sigma upper limit of 0.012 counts/s 
can be
given for the second orbit.
 Based on this result, we estimated a decay slope of 2.8+/-0.6.

The X-ray data can be fitted by a single power law with a photon
index Gamma=1.7+-0.8 and the absorption column density fixed to the Galactic
value of NH=1.68e21
cm-2 (Dickey & Lockman, 1990) with chi2/dof=4/3.

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