TITLE: GCN CIRCULAR NUMBER: 16308 SUBJECT: GRB 140518A: Continued RATIR Optical and NIR Observations DATE: 14/05/19 15:01:09 GMT FROM: Nat Butler at Az State U Nat Butler (ASU), Alan M. Watson (UNAM), Alexander Kutyrev (GSFC), William H. Lee (UNAM), Michael G. Richer (UNAM), Chris Klein (UCB), Ori Fox (UCB), J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (ORAU/GSFC), Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz (UCSC), José A. de Diego (UNAM), Leonid Georgiev (UNAM), Jesús González (UNAM), Carlos Román-Zúñiga (UNAM), Neil Gehrels (GSFC), and Harvey Moseley (GSFC) report: We observed the field of GRB 140518A (Melandri, et al., GCN 16298) with the Reionization and Transients Infrared Camera (RATIR; www.ratir.org) on the 1.5m Harold Johnson Telescope at the Observatorio Astronómico Nacional on Sierra San Pedro Mártir from 2014/05 19.24 to 2014/05 19.46 UTC (20.37 to 25.71 hours after the BAT trigger), obtaining a total of 2.47 hours exposure in the r and i bands and 2.06 hours exposure in the Z an J bands. For a source at the optical transient position (Zheng et al., GCN 16299), in comparison with the SDSS DR9 and 2MASS, we obtain the following upper limits (3-sigma): r > 22.03 i > 22.20 Z > 21.28 J > 21.07 These magnitudes are in the AB system and are not corrected for Galactic extinction in the direction of the GRB. Compared to our observations last night (Cucchiara, et al., GCN 16302), during which the source faded approximately as t^(-0.5), the source has now apparently faded more rapidly as t^(-1) or faster. We thank the staff of the Observatorio Astronómico Nacional in San Pedro Mártir.