TITLE: GCN CIRCULAR NUMBER: 17876 SUBJECT: GRB 150527A: RATIR Afterglow Detection DATE: 15/05/27 08:04:18 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 150527A (Evans, et al., GCN 17874) 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 2015/05 27.29 to 2015/05 27.32 UTC (13.2 to 54.6 minutes after the BAT trigger), obtaining a total of 0.58 hours exposure in the r, i, and z bands. A source is detected within the Swift-XRT error circle. In comparison with the USNO-B1 catalog, we obtain the following detections and upper limit (3-sigma): r 21.17 +/- 0.10 i 20.83 +/- 0.14 z > 19.50 These magnitudes are in the AB system and are not corrected for Galactic extinction in the direction of the GRB. Additional observations are ongoing. We thank the staff of the Observatorio Astronómico Nacional in San Pedro Mártir.