TITLE: GCN CIRCULAR NUMBER: 27754 SUBJECT: GRB 200517A: Swift-XRT afterglow detection DATE: 20/05/18 15:06:08 GMT FROM: Jeffrey Gropp at PSU B. Sbarufatti (PSU), D.N. Burrows (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), T. Sbarrato (INAF-OAB), P. D'Avanzo (INAF-OAB), M.G. Bernardini (INAF-OAB), J. D. Gropp (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 200517A (Niwano et al. GCN Circ. 27750) in a series of observations tiled on the sky. The total exposure time is 1.1 ks, distributed over 7 tiles; the maximum exposure at a single sky location was 388 s. The data were collected between T0+8.0 ks and T0+8.3 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. Using 366 s of PC mode data and 2 UVOT images, we find an enhanced XRT position (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec = 17.69837, -50.92242 which is equivalent to: RA (J2000): 01h 10m 47.61s Dec(J2000): -50d 55' 20.7" with an uncertainty of 3.3 arcsec (radius, 90% confidence). This position is 20.7 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 https://www.swift.ac.uk/xrt_products/TILED_GRB00090/Source1.php. The results of the full analysis of the tiled XRT observations are available at https://www.swift.ac.uk/xrt_products/TILED_GRB00090. This circular is an official product of the Swift-XRT team.