TITLE: GCN CIRCULAR NUMBER: 35251 SUBJECT: GRB 231129C: Swift-XRT afterglow detection DATE: 23/12/02 14:30:18 GMT FROM: Phil Evans at U of Leicester J. D. Gropp (PSU), S. Dichiara (PSU), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), M.G. Bernardini (INAF-OAB), E. Ambrosi (INAF-IASFPA) , M. Capalbi (INAF-IASFPA), J.A. Kennea (PSU) and P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team: Swift-XRT has conducted further observations of the field of the Fermi/GBM-detected burst GRB 231129C. The observations now extend from T0+34.8 ks to T0+172.6 ks. The source previously reported, "Source 2", is believed to be the afterglow. The position of this source is RA, Dec=11.1769, -81.9936 which is equivalent to: RA (J2000): 00:44:42.45 Dec(J2000): -81:59:37.0 with an uncertainty of 9.5 arcsec (radius, 90% confidence). This position is 22.4 arcmin from the Fermi/GBM position. We cannot determine at the present time whether the source is fading. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00021633. The results of the full analysis of the tiled XRT observations are available at https://www.swift.ac.uk/xrt_products/TILED_GRB00117. This circular is an official product of the Swift-XRT team.