[vsnet-grb-info 3580] GRB 060805B: X-ray Afterglow Detection, Spectral/Spatial/Temporal Properties

[GCN Circulars]

TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  5414
SUBJECT: GRB 060805B: X-ray Afterglow Detection, Spectral/Spatial/Temporal Properties
DATE:    06/08/07 17:45:13 GMT
FROM:    Nat Butler at MIT/CSR  <nrbutler at space.mit.edu>

N. Butler (UC Berkeley) reports:

We report the results of a spectral/spatial/temporal analysis of the
Swift target-of-opportunity observation of the X-ray afterglow to
GRB060805B (GCN 5407).  We detect a bright and fading X-ray source <~0.7
arcmin from the center of the IPN error region.  Using 130 cts (0.3-10 keV)
from a total exposure of 16.7 ksec for the time interval 126-164 ksec after
the IPN trigger, the count rate fades as t^-alpha, with alpha=-2.4+/-1.1.

The spectrum is fit by an absorbed powerlaw, with column density
N_H = (1.3+/-1.1) 10^21 cm^-2, consistent with the Galactic value in the
source direction.  Also, we find photon index Gamma=2.1+/-0.4 and
unabsorbed flux (4.4+/-1.1) 10^(-13) erg cm^-2 s^-1.

We determine the following position for the transient, with respect to
the DSS positions of 23 optical sources and the XRT positions of 7 X-ray
sources and including an estimate of the systematic error:

        RA, Dec: 18 10 05.41  +58 09 18.1 ; +/- 2.6" (J2000, 90% Conf.)

We note that the X-ray source is near but not spatially consistent with
a R~18.5 mag source in the DSS at RA, Dec: 18 10 5.64, +58 09 19.4.