TITLE: GCN CIRCULAR NUMBER: 14680 SUBJECT: GRB 130518A: P60 Afterglow Observations DATE: 13/05/20 04:03:37 GMT FROM: S. Bradley Cenko at Caltech S. B. Cenko (UC Berkeley) reports on behalf of a larger collaboration: We have imaged the location of the Fermi GBM (Xiong et al., GCN 14674), LAT (Omodei et al., GCN 14675), Swift BAT (Cummings et al., GCN 14676), and Konus-Wind (Golenetskii et al., GCN 14677) GRB 130518A with the robotic Palomar 60 inch telescope. Observations were obtained in the r' and i' filters beginning at 10:24 UT on 2013 May 19 (~ 0.85 d after the GBM trigger). We detect the optical afterglow (Evans et al., GCN 14678; Troja et al., GCN 14679) in both filters. Using several nearby point sources from SDSS for calibration, we measure a magnitude of r' = 19.3 at this time.