TITLE: GCN CIRCULAR NUMBER: 16300 SUBJECT: GRB 140518A: P60 i-/z-band detections DATE: 14/05/18 12:22:01 GMT FROM: Daniel Perley at Caltech D. A. Perley (Caltech) reports on behalf of a larger collaboration The Palomar 60-inch telescope responded automatically to the Swift trigger for GRB 140518A (Melandri et al., GCN 16298) and began a repeating cycle of 60-second exposures in r, i, and z-band observations at 09:22:28 UT, 4.70 minutes after the burst. We weakly detect the afterglow reported by Zheng et al. (GCN 16299) in the i and z filters, but not in r-band. Only marginal detections are evident in any individual exposure in any filter, but a stack of the first six exposures in each band gives magnitudes (calibrated relative to SDSS) of: r > 20.31 (2 sigma) i = 19.03 +/- 0.16 z = 18.20 +/- 0.17 at a mid-time of approximately 16 minutes after the burst.