TITLE: GCN CIRCULAR NUMBER: 26121 SUBJECT: GRB 191031D: RATIR Optical and NIR Observations DATE: 19/11/01 04:40:51 GMT FROM: Alan M Watson at UNAM 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), Harvey Moseley (GSFC), John Capone (UMD), V. Zach Golkhou (U. Wash.), and Vicki Toy (UMD) report: We observed the field of GRB 191031D (Fermi GBM Team, GCN Circ. 26111; D'Elia et al., GCN Circ. 26112) 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 2019/11 1.09 to 2019/11 1.12 UTC (4.65 to 5.49 hours after the BAT trigger), obtaining a total of 0.56 hours exposure in the r and i bands, 0.23 hours exposure in the Z and Y bands, and 0.06 hours exposures in the J and H bands. For a source within the Swift-XRT error circle, in comparison with the USNO-B1 and 2MASS catalogs, we obtain the following upper limits (3-sigma): r > 22.94 i > 23.17 Z > 21.50 Y > 21.40 J > 19.44 H > 19.33 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.