TITLE: GCN CIRCULAR NUMBER: 45623 SUBJECT: GRB 260915A: Swift-XRT afterglow detection DATE: 26/09/18 06:26:48 GMT FROM: Phil Evans at U of Leicester K.L. Page (U. Leicester), M. Perri (SSDC & INAF-OAR), V. D'Elia (SSDC & INAF-OAR), J.A. Kennea (PSU), S. Lanava (PSU), A.P. Beardmore (U. Leicester), J.P. Osborne (U. Leicester), B. Sbarufatti (INAF-OAB) and P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team: Swift-XRT has performed follow-up observations of the SVOM/ECLAIRs-detected burst GRB 260915A. We searched for X-ray sources in 2.7 ks of Photon Counting (PC) mode data. The total exposure at the position of the afterglow (see below) is 2.7 ks, obtained between T0+174.4 ks and T0+246.9 ks. An uncatalogued X-ray source is detected within the estimated 3-sigma SVOM/MXT error region (49 arcsec). While the source does not fade during the Swift-XRT observation, the measured flux of 2.0 (+7.4, -1.4)e-13 erg cm^-2 s^-1 (0.3-10 keV) is more than an order of magnitude below the EP value of 7.8 (+/- 0.4)e-12 erg cm^-2 s^-1 (0.5-10 keV) at T0+6 ks, reported in GCN Circ. 45587. This source is therefore believed to be the afterglow. The position of this source is RA, Dec=8.1546, +8.2487 which is equivalent to: RA (J2000): 00h 32m 37.11s Dec(J2000): +08d 14' 55.5" with an uncertainty of 8.5 arcsec (radius, 90% confidence). This position is 23 arcsec from the SVOM/MXT position, and 11 arcsec from the EP-FXT position. The results of the XRT-team automatic analysis are available at https://www.swift.ac.uk/xrt_products/00021912. The results of the full analysis of the XRT observations are available at https://www.swift.ac.uk/ToO_GRBs/00021912. This circular is an official product of the Swift-XRT team.