TITLE: GCN CIRCULAR NUMBER: 20655 SUBJECT: GRB 170208B: RATIR Optical and NIR Observations DATE: 17/02/09 23:48:46 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), Ori Fox (STScI), J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (UVI), Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz (UCSC), 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 170208B (Siegel, et al., GCN 20632) 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 2017/02 9.11 to 2017/02 9.47 UTC (3.98 to 12.65 hours after the BAT trigger), obtaining a total of 6.02 hours exposure in the r and i bands and 2.52 hours exposure in the Z and Y bands. We do not detect either the GROND (Kruehler, et al., GCN 20640) source or the WHT (Wiersema, et al., GCN 20647) source. In comparison with the USNO-B1 and 2MASS catalogs, we obtain the following upper limits (3-sigma): r > 23.56 i > 23.43 Z > 22.64 Y > 22.55 These magnitudes are in the AB system and are not corrected for Galactic extinction in the direction of the GRB. The lack of detection of the WHT source is consistent with this source being reddened due to dust or due to a high-z origin if the GROND source is not the GRB host galaxy. The first possibility is also suggested by the significant X-ray column density relative to the Galactic value (Kennea, et al., GCN 20637). We thank the staff of the Observatorio Astronómico Nacional in San Pedro Mártir.