GCN Circular 18671
A. Melandri, P. D'Avanzo (INAF-OAB) A. D'Ai (INAF-IASFPA), J.A. Kennea (PSU), B. Sbarufatti (INAF-OAB/PSU), D.N. Burrows (PSU), K.L. Page (U. Leicester), C. Pagani (U. Leicester), A.P. Beardmore (U. Leicester), A. Maselli (INAF-IASFPA) 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 151205C (Nakajima et al. GCN Circ. 18666) in a series of observations tiled on the sky. The total exposure time is 2.5 ks, distributed over 7 tiles; the maximum exposure at a single sky location was 790 s. The data were collected between T0+11.1 ks and T0+22.8 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 ~0.03 ct s^-1, corresponding to a 0.3-10 keV observed flux of 7.6e-13 to 1.1e-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 http://www.swift.ac.uk/xrt_products/TILED_GRB00049. This circular is an official product of the Swift-XRT team.