TITLE: GCN CIRCULAR NUMBER: 25542 SUBJECT: GRB 190828A: Swift-XRT observations DATE: 19/08/29 09:46:09 GMT FROM: Paolo D'Avanzo at INAF - OAB J.A. Kennea (PSU), A.P. Beardmore (U. Leicester), J.P. Osborne (U. Leicester), M.G. Bernardini (INAF-OAB), E. Ambrosi (INAF-IASFPA) , M. Capalbi (INAF-IASFPA), B. Sbarufatti (PSU), D.N. Burrows (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 190828A (Sugita et al. GCN Circ. 25502) 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 393 s. The data were collected between T0+48.4 ks and T0+49.8 ks, and are entirely in Photon Counting (PC) mode. No X-ray sources have been detected. The 3-sigma upper limit in the field (not including the regions where the tiles overlap) ranges from ~0.02 to ~0.15 ct s^-1, corresponding to a 0.3-10 keV observed flux of 9.9e-13 to 5.8e-12 erg cm^-2 s^-1 (assuming a typical GRB spectrum). The results of the XRT-team automatic analysis of the tiled XRT observations, including a position-specific upper limit calculator, are available at https://www.swift.ac.uk/xrt_products/TILED_GRB00086. This circular is an official product of the Swift-XRT team.