GCN Circular 4006
J. A. Kennea, D. N. Burrows, D. Grupe, P. Roming (PSU), J. Osborne (U. Leicester), S. T. Holland (GSFC/USRA) and N. Gehrels (GSFC) report on behalf of the Swift team: At September 20th 22:08 UT, Swift began a 10ks TOO observation of the Integral discovered burst GRB050918 (GCN 4002). Analysis of ground processed data from Swift/XRT reveals a previously uncatalogued faint X-ray point source inside the 2.8 arcminute Integral error circle, at the following coordinates: RA(J2000): 17:50:28.7, Dec(J2000): -25:24:41.2. The uncertainty on this position is estimated to be 7 arcseconds radius (90% containment). This position is 34 arcseconds from the center of the Integral error circle given in GCN 4002. There is no evidence of fading in this source, however as this observation occured more than 2 days after the burst this result is expected. Further observations will be required to determine if this source is the afterglow of GRB050918. A UVOT V-band image shows no new source, with respect to the DSS, inside the INTEGRAL 2.8 arcminute radius error circle. The 5-sigma limiting magnitude in a circular aperture with a radius of six arcseconds is V_lim=19.3.