TITLE: GCN CIRCULAR NUMBER: 23096 SUBJECT: GRB 180806A/180806.98: RATIR Optical Observations of MASTER OT J004613.05+242014.1 DATE: 18/08/07 17:52:13 GMT FROM: Alan M. Watson at Instituto de Astronomia UNAM Alan M. Watson (UNAM), Nat Butler (ASU), 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 the Fermi GRB 180806A/180806.98 (Malacaria et al., GCN Circ. 23095) 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 2018/08 7.47 to 2018/08 7.51 UTC (12.69 to 13.71 hours after the GBM trigger), obtaining a total of 0.71 hours exposure in the r and i bands. We detect a source at the coordinates of the MASTER OT reported by Lipunov et al. (GCN Circ. 23091). In comparison with the SDSS catalog, we obtain the following magnitudes: r = 20.21 +/- 0.02 i = 19.92 +/- 0.01 These magnitudes are in the AB system and are not corrected for Galactic extinction in the direction of the GRB. These magnitudes are similar to the w magnitude reported by Butler et al. (GCN Circ. 23094) and further confirm the fading compared to the earlier MASTER magnitude reported by Watson et al. (GCN Circ. 23092). We thank the staff of the Observatorio Astronómico Nacional in San Pedro Mártir.