TITLE: GCN CIRCULAR NUMBER: 31902 SUBJECT: GRB 220412A: Continued RATIR Observations and Steepening of the Light Curve DATE: 22/04/14 20:00:57 GMT FROM: Alan M Watson at UNAM Alan M. Watson (UNAM), Nat Butler (ASU), Eleonora Troja (UTV), Alexander Kutyrev (GSFC), William H. Lee (UNAM), 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 (PSU), and Océlotl López (UNAM) report: We observed the field of GRB 220412A (Klingler et al. GCN 31881) 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 2022-04-14 03:28 to 07:30 UTC (44.9 to 48.9 hours after the trigger) obtaining 2.31 hours of exposure in the i band. In comparison with the SDSS DR9 catalog, the afterglow candidate reported by Watson et al. (GCN Circ. 31882, 31898) is detected at i = 21.51 +/- 0.10. We note that the optical light curve appears to have steepened. The temporal index between our observations at 21 hours (Watson et al., GCN Circ 31898) and 47 hours is close to -1.0. Further observations are continuing. We thank the staff of the Observatorio Astronómico Nacional in San Pedro Mártir.