TITLE: GCN CIRCULAR NUMBER: 28151 SUBJECT: GRB 200716C: CrAO, Terskol, Assy-Turgen optical observations DATE: 20/07/21 15:34:11 GMT FROM: Alexei Pozanenko at IKI, Moscow A. Pozanenko (IKI), S. Belkin (IKI), V. Rumyantsev (CrAO), A. Gorshkov (INASAN), V. Kim (AFIF, Pulkovo Observatory), N. Pankov (HSE), K. Kamyshnikov (HSE), M. Krugov (AFIF), A. Volnova (IKI), E. Mazaeva (IKI) report on behalf of larger GRB follow-up collaboration: We observed GRB 200716C (Fermi GBM team, GCN 28123; Ukwatta et al GCN 28124; Torii et al., GCN 28139; Xue et al., GCN 28145; Frederiks et al., GCN 28147) with ZTSH 2.6m telescope of CrAO observatory, Zeiss-2000 of Terskol observatory, and AZT-20 telescope of Assy-Turgen observatory. The optical afterglow (Ukwatta et al., GCN 28124; Lipunov et al., GCN 28125; Hu et al., GCN 28126; Kumar et al., GCN 28138; Gokuldass et al., GCN 28146; Jelinek et al., GCN 28149) and possible host galaxy (D’Avanzo et al., GCN 28132) is detected in a stacked image. Preliminary photometry of the (afterglow + possible host galaxy) is following Date UT start t-T0 Filter Exp. OT Err. UL Telescope (mid, days) (s) 2020-07-17 19:17:52 0.84735 R 29*60 19.04 0.03 22.0 ZTSh 2020-07-17 19:50:49 0.87023 R 30*60 19.21 0.03 21.9 ZTSh 2020-07-18 18:33:32 1.83323 R 24*120 19.21 0.06 22.1 Zeiss-2000 2020-07-18 19:25:19 1.85253 R 17*60 19.21 0.06 22.1 ZTSh 2020-07-19 17:15:50 2.78066 r' 52*60 19.31 0.03 22.4 AZT-20 The photometry is based for R-calibration on the star USNO-B1.0_id R 1196-0207871 16.18 and nearby SDSS stars for r' calibration SDSS-DR12_id r J130423.13+294053.3 15.970 J130352.15+293733.9 16.592 J130416.16+293906.8 16.914 The above photometry besides of the first observation is consistent with a brightness of possible host in USNO-B1.0 (R2=19.23) and in SDSS DR12 (r'= 19.301 +/- 0.026). We may conclude that we detected afterglow only in the first observation on 0.84735 days after trigger at R=19.04 +/- 0.03.