[vsnet-grb-info 7216] GRB 090107B: Swift-XRT detection of possible afterglow

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  8789
SUBJECT: GRB 090107B: Swift-XRT detection of possible afterglow
DATE:    09/01/07 21:09:39 GMT
FROM:    Matteo Perri at ISAC/ASDC  <perri at asdc.asi.it>

M. Perri (ASDC) and P. Evans (U. Leicester) report on behalf of the
Swift-XRT team:

Swift began observing the field of the INTEGRAL GRB 090107B (Gotz et
al., GCN Circ. 8786) 4.2 ks after the trigger. A single uncatalogued
source was identified within the IBIS/ISGRI error circle.

Using 1314 s of XRT Photon Counting mode data and 2 UVOT images, we find
an astrometrically corrected X-ray position (using the XRT-UVOT alignment
and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec =
284.81750, 59.59510 which is equivalent to:

RA (J2000):  18 59 16.21
Dec (J2000): +59 35 42.3

with an uncertainty of 1.8 arcsec (radius, 90% confidence). The source
lies 21 arcsec from the IBIS/ISGRI centroid and has a count rate of
~0.25 counts/s during this observation.

Currently we cannot determine if this source is fading, and therefore
cannot confirm if this source is associated with GRB 090107B.
Observations of this source are on-going.

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