TITLE: GCN CIRCULAR NUMBER: 19993 SUBJECT: GRB 161004A: RATIR Optical and NIR Observations DATE: 16/10/05 12:32:05 GMT FROM: Eleonora Troja at GSFC Eleonora Troja (GSFC), Nat Butler (ASU), Alan M. Watson (UNAM), Alexander Kutyrev (GSFC), William H. Lee (UNAM), Michael G. Richer (UNAM), Ori Fox (STScI), J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (UVI), 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), Harvey Moseley (GSFC), John Capone (UMD), V. Zach Golkhou (ASU), and Vicki Toy (UMD) report: We observed the field of GRB 161004A (Evans, et al., GCN 19979) 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 2016/10 5.10 to 2016/10 5.22 UTC (13.49 to 16.23 hours after the BAT trigger), obtaining a total of 1.73 hours exposure in the r and i bands and 0.65 hours exposure in the Z, Y, J, and H bands. For a source within the Swift-UVOT error circle (Breeveld & Evans, GCN 19984), in comparison with the USNO-B1 and 2MASS catalogs, we obtain the following upper limits (3-sigma): r > 23.3 i > 23.2 Z > 22.4 Y > 21.8 J > 21.3 H > 19.4 These magnitudes are in the AB system and are not corrected for Galactic extinction in the direction of the GRB. We thank the staff of the Observatorio Astronómico Nacional in San Pedro Mártir.