GCN Circular 15182
Rhaana Starling (U. Leicester) reports on behalf of the Swift team We report further analysis of Swift follow-up of the possible weak INTEGRAL GRB detected on 4th September 2013 (GCN 15180). The full XRT dataset, comprising 6.28 ks of exposure and beginning 2 hours after the INTEGRAL detection, shows no evidence for a source at the INTEGRAL Weak alert position. The 3-sigma upper limit on the count rate at this position, using Bayesian statistics (Kraft, Burrows & Nousek 1991), is 2.2e-3 count/s. We do find a new X-ray source at position RA (J2000) = 17 08 03.52 Dec (J2000) = -32 02 31.5 or RA, Dec = 257.0147, -32.0421 degrees with an uncertainty of 3.9 arcseconds (radius, 90% confidence). This is 7.3 arcminutes from the INTEGRAL position, and lies outside the given 3.6 arcminute radius error circle. This source is 4.9-sigma significant, and has a count rate of (4.4 +3.6/-2.5)e-3 count/s. A source is listed at this position in a number of optical and nIR surveys, and in the Atlas of Radio/X-ray associations (Flesch 2010) where it is classified as a double radio lobe. Three further low-significance (=<3-sigma) sources are present in the field. The association of any of these with the INTEGRAL trigger is unclear. No further Swift observations of this source are planned at this time.