TITLE: GCN CIRCULAR NUMBER: 19809 SUBJECT: GRB 160816A: RATIR Optical and NIR Observations DATE: 16/08/17 09:26:10 GMT FROM: Eleonora Troja at GSFC Eleonora Troja (GSFC), Alan M. Watson (UNAM), Nat Butler (ASU), Alexander Kutyrev (GSFC), William H. Lee (UNAM), Michael G. Richer (UNAM), Ori Fox (STScI), J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (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), Harvey Moseley (GSFC), John Capone (UMD), V. Zach Golkhou (ASU), and Vicki Toy (UMD) report: We observed the field of the Fermi GRB 160816A (Mailyan, et al., GCN 19804; Racusin et al. 19802) 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 2017-08-17 06:15 to 07:44 UTC (12.8 to 14.2 hours after the GBM trigger), obtaining a total of 0.71 hours exposure in the r and i bands and 0.30 hours exposure in the Z, Y, J, and H bands. For a source within the Swift/XRT error circle (Kennea et al., GCN 19806), in comparison with the USNO-B1 and 2MASS catalogs, we obtain the following detections: r = 21.05 +/- 0.05 i = 20.79 +/- 0.04 Z = 20.61 +/- 0.07 Y = 20.32 +/- 0.08 J = 20.16 +/- 0.09 H = 19.95 +/- 0.10 These magnitudes are in the AB system and are not corrected for Galactic extinction in the direction of the GRB. The source position is RA,Dec(J2000)=21:29:38.549,+37:07:58.79 with an uncertainty of 0.5 arcsec. Our position is consistent with the candidate reported from Guidorzi, et al. (GCN 19808). We thank the staff of the Observatorio Astronómico Nacional in San Pedro Mártir. Further observations are on-going.