TITLE: GCN CIRCULAR NUMBER: 29302 SUBJECT: GRB 210112A: Mondy optical observations DATE: 21/01/13 20:28:18 GMT FROM: Alexei Pozanenko at IKI, Moscow N. Pankov (HSE), A. Pozanenko (IKI), E. Klunko (ISTP), S. Belkin (IKI) report on behalf of GRB IKI FuN: We observed the field of GRB 210112A (Ambrosi et al., GCN 29289; Ursi et al., GCN #9293) with AZT-33IK telescope of Sayan observatory (Mondy) starting on 2021-01-12 (UT) 20:41:40. The optical afterglow (Ambrosi et al., GCN 29289; Kann et al., GCNs 29296, 29300) is not detected in stacked image in R-filter. The non detection of the afterlow is consistent with other non-detections in R-filter (Novichonok et al., GCN 29292; Gupta et al., GCN 29301). Preliminary photometry of the optical transient in a combined image is following Date UT start t-T0 Filter Exp. OT Err. UL(3sigma) (mid, days) (s) 2021-01-12 20:41:40 0.80738 R 18*120 n/d n/d 22.4 The photometry is based on the nearby USNO-B1.0 stars.