TITLE: GCN CIRCULAR NUMBER: 18112 SUBJECT: GRB 150801A: Swift-XRT observations DATE: 15/08/03 17:53:41 GMT FROM: Boris Sbarufatti at INAF-OAB/IASFPA A. Melandri (INAF-OAB), P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), D.N. Burrows (PSU), T.G.R. Roegiers (PSU), L.M. McCauley (PSU), A.P. Beardmore (U. Leicester), B.P. Gompertz (U. Leicester) 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 150801A (Ishikawa et al. GCN Circ. 18102) in a series of observations tiled on the sky. The total exposure time is 3.8 ks, distributed over 4 tiles; the maximum exposure at a single sky location was 1.6 ks. The data were collected between T0+50.8 ks and T0+62.9 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 ~0.006 to ~0.009 ct s^-1, corresponding to a 0.3-10 keV observed flux of 2.4e-13 to 3.8e-13 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 http://www.swift.ac.uk/xrt_products/TILED_GRB00047. This circular is an official product of the Swift-XRT team.