TITLE: GCN CIRCULAR NUMBER: 30973 SUBJECT: GRB 211023B: RATIR Optical and NIR Upper Limits DATE: 21/10/24 14:34:57 GMT FROM: Alan M Watson at UNAM <alan@astro.unam.mx> Alan M. Watson (UNAM), Nat Butler (ASU), Alexander Kutyrev (GSFC), William H. Lee (UNAM), Eleonora Troja (GSFC), Michael G. Richer (UNAM), Ori Fox (STScI), J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Enrico Ramirez-Ruiz (UCSC), Jesús González (UNAM), Carlos Román-Zúñiga (UNAM), Harvey Moseley (GSFC), Rosa L. Becerra (UNAM), Simone Dichiara (UMD), and Océlotl López (UNAM) report: We observed the field of GRB 211023B (Dichiara et al., GCN 30960) with the Reionization and Transients Infrared Camera (RATIR) on the 1.5m Harold Johnson Telescope at the Observatorio Astronómico Nacional on Sierra San Pedro Mártir from 2021/10 24.49 to 2021/10 24.53 UTC (14.54 to 15.54 hours after the BAT trigger), obtaining a total of 0.73 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 UVOT error circle, in comparison with the SDSS DR9 and 2MASS catalogs, we obtain the following detections and upper limits (3-sigma): r > 22.4 i > 22.1 Z > 20.6 Y > 20.3 J > 21.0 H > 20.7 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.