TITLE: GCN CIRCULAR NUMBER: 14606 SUBJECT: GRB 130427A: Continued RATIR Optical and NIR Observations DATE: 13/05/08 16:34:04 GMT FROM: Alan M. Watson at Instituto de Astronomia UNAM Alan M. Watson (UNAM), Nat Butler (ASU), 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 (UCSC), 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 have been monitoring GRB 130427A 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. We have precise and homogeneous photometry for all nights except 2013 May 6. During the first night the optical afterglow is well-fitted by a power law with an index of -1. However, around 1 day after the burst there is a break, and the power law steepens. Our photometry in gri from 2 to 11 days is well-fitted by a power law with an index very close to -1.5 plus a constant contribution with i = 21.23 ± 0.05, g-i = 0.74 ± 0.12, and r-i = 0.05 ± 0.05, consistent with the SDSS DR9 photometry of the presumed host galaxy. We see no evidence for an additional component such as the one mentioned by Xu et al. (GCN Circular 14597). Further observations are planned. We thank the staff of the Observatorio Astronómico Nacional in San Pedro Mártir.