TITLE: GCN CIRCULAR NUMBER: 15361 SUBJECT: GRB 131018B: Swift-XRT observations DATE: 13/10/20 19:35:14 GMT FROM: Paolo D'Avanzo at INAF-OAB P. D'Avanzo, A. Melandri, M. G. Bernardini (INAF-OAB), P. A. Evans (U. Leicester) report on behalf of the Swift-XRT team: We have analysed 2.8 ks of XRT data for the Fermi/LAT-detected burst: GRB 131018B (Vianello et al., GCN 15357; Zhang, GCN 15360), from 83.1 ks to 95.2 ks after the Fermi/LAT trigger. The data are entirely in Photon Counting (PC) mode. An uncatalogued X-ray source is detected within the Fermi/LAT error circle. The refined XRT position is RA, Dec = 304.53693, +23.18759 which is equivalent to: RA (J2000): 20 18 08.86 Dec(J2000): +23 11 15.3 with an uncertainty of 4.9 arcsec (radius, 90% confidence). This position is 514 arcsec from the Fermi/LAT position. We cannot determine at the present time whether the source is fading. We note the presence of two further sources within the LAT error box. Source #2 has the following position RA, Dec = 304.41156, +23.16636 which is equivalent to: RA (J2000): 20 17 38.77 Dec(J2000): +23 09 58.9 with an uncertainty of 5.4 arcsec (radius, 90% confidence). Source #3 has the following position RA, Dec = 304.52361 +23.06517 which is equivalent to: RA (J2000): 20 18 05.67 Dec(J2000): +23 03 54.6 with an uncertainty of 6.0 arcsec (radius, 90% confidence). Both sources are present in the Swift-XRT point source catalogue (D'Elia et al. 2013; A&A 551, A142) and are likely not related with GRB 131018B. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00020308. This circular is an official product of the Swift-XRT team. [GCN OPS NOTE(22oct13): Per author's reuqest, the affiliations of the authors was corrected.]