TITLE: GCN CIRCULAR NUMBER: 20996 SUBJECT: GRB 170405A: RATIR Optical and NIR Observations DATE: 17/04/06 15:58:54 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), Jesús González (UNAM), Carlos Román-Zúñiga (UNAM), Harvey Moseley (GSFC), John Capone (UMD), V. Zach Golkhou (ASU), and Vicki Toy (UMD) report: We observed the field of GRB 170405A (Troja, et al., GCN 20984) 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 2017/04 6.23 to 2017/04 6.48 UTC (10.93 to 16.85 hours after the BAT trigger), obtaining a total of 3.84 hours exposure in the r and i bands and 1.62 hours exposure in the Z, Y, J, and H bands. For a source within the Swift-UVOT error circle (Troja, et al., GCN 20984), in comparison with the USNO-B1 and 2MASS catalogs, we obtain the following detections: r 22.67 +/- 0.05 i 21.83 +/- 0.04 Z 21.26 +/- 0.07 Y 21.14 +/- 0.07 J 20.75 +/- 0.07 H 20.56 +/- 0.08 These magnitudes are in the AB system and are not corrected for Galactic extinction in the direction of the GRB. The nearby object noted by Malesani et al., (GCN 20988) is detected in all our images and might affect our photometric measurements. The reported values should be therefore considered as preliminary. We thank the staff of the Observatorio Astronómico Nacional in San Pedro Mártir. Further observations are planned.