TITLE: GCN CIRCULAR NUMBER: 31870 SUBJECT: GRB 220408A: RATIR Optical and NIR Observations DATE: 22/04/10 17:38:55 GMT FROM: Alan M Watson at UNAM 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 220408A (Caputo et al., GCN Circ. 31848) 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 2022/04 9.13 to 2022/04 9.49 UTC (20.98 to 29.45 hours after the BAT trigger), obtaining a total of 3.27 hours exposure in the r and i bands and 2.10 hours exposure in the Z, Y, 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 weak detection and 3-sigma upper limits: r > 23.76 i > 23.45 Z > 21.36 Y > 22.04 J > 21.79 H = 21.27 +/- 0.23 These magnitudes are in the AB system and are not corrected for Galactic extinction in the direction of the GRB. We note that while we have a formal detection in H, the large errors call it into doubt. Our limit in r is consistent with the fainter and slightly earlier detection at r = 24.1 reported by Zhu et al. (GCN Circ. 31864). We thank the staff of the Observatorio Astronómico Nacional in San Pedro Mártir.