TITLE: GCN CIRCULAR NUMBER: 18687 SUBJECT: GRB 151212A: Swift-XRT afterglow detection DATE: 15/12/12 20:48:03 GMT FROM: Phil Evans at U of Leicester T.G.R. Roegiers (PSU), S.L. Gibson (U. Leicester), J.P. Osborne (U. Leicester), P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), A. D'Ai (INAF-IASFPA), L.M. McCauley (PSU), J.A. Kennea (PSU) and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team: Swift-XRT has performed follow-up observations of the MAXI-detected burst GRB 151212A (Nakahira et al. GCN Circ. 18685) in a series of observations tiled on the sky. The total exposure time is 1.3 ks, distributed over 7 tiles; the maximum exposure at a single sky location was 437 s. The data were collected between T0+8.4 ks and T0+8.6 ks, and are entirely in Photon Counting (PC) mode. An uncatalogued X-ray source is detected and is above the RASS limit, and is therefore likely the GRB afterglow. The position of this source is RA, Dec=68.1521, -3.9615 which is equivalent to: RA (J2000): 04:32:36.50 Dec(J2000): -03:57:41.3 with an uncertainty of 5.2 arcsec (radius, 90% confidence). This position is 11.5 arcmin from the MAXI position. We cannot determine at the present time whether the source is fading. The results of the XRT-team automatic analysis of the likely afterglow are at http://www.swift.ac.uk/xrt_products/TILED_GRB00050/index_1.php. The results of the full analysis of the tiled XRT observations are available at http://www.swift.ac.uk/xrt_products/TILED_GRB00050. This circular is an official product of the Swift-XRT team.