GRB 210104B: Assy optical upper limit

We observed the field of GRB 210104B (Laha et al., GCN 29243) with AZT-20 1.5-m telescope of Assy-Turgen Observatory (Assy) starting on Jan. 04 (UT) 22:31:15. We did not find any optical counterpart in our 20x60s stacked image in the enhanced XRT position (Evans et al., GCN 29253) down to an upper limit R~23.2 (see also Hu et al., GCN 29249 and Fu et al., GCN 29250). Preliminary photometry of the filed is the following: Date UT start t-T0 Filter Exp. OT Err. UL(3-sigma) FWHM (mid, days) (s) (") 2021-01-04 22:31:15 0.06325 r' 20*60 n/d n/d 23.2 2.3 Further observations on this object are not planned except personal request.