TITLE: GCN CIRCULAR NUMBER: 14690 SUBJECT: Swift XRT observation of GRB 130518B DATE: 13/05/21 19:24:38 GMT FROM: Boris Sbarufatti at INAF-OAB/IASFPA Boris Sbarufatti (INAF-OAB/PSU) reports on behalf of the Swift XRT team We have analysed 4.2 ks of XRT data for GRB 130518B (Cummings GCN Circ. 14862), from 184.0 ks to 196.1 ks after the BAT trigger. The data are all in Photon Counting (PC) mode. No bright X-ray afterglow is detected inside the refined BAT error circle. The 3sigma upper limit is of 4.3 x 10^-3 cts/s. This corresponds to an observed 0.3-10 keV flux of 1.6 x 10^-13 erg/cm2/s (assuming a typical GRB spectrum with photon spectral index of 2). If we consider the Galactic absorption in this direction (3.5 x 10^20 cm^-2; Kalberla et al. 2005) this corresponds to an unabsorbed flux of 1.8 x 10^-13 erg/cm2/s.