TITLE: GCN CIRCULAR NUMBER: 32684 SUBJECT: GRB 221009A: Sintez-Newton/CrAO optical observations DATE: 22/10/11 13:01:20 GMT FROM: Alexei Pozanenko at IKI, Moscow S. Belkin (IKI, HSE), S. Nazarov (CrAO), A. Pozanenko (IKI), N. Pankov (HSE) report on behalf of IKI GRB FuN: We observed GRB 221009A/Swift J1913.1+1946 (Dichiara et al., GCN 32632; Kennea and Williams, GCN 32635; Veres et al., GCN 32636; Bissaldi et al., GCN 32636; Svinkin et al., GCN 32641; Piano et al., GCN 32657; Pillera et al., GCN 32658; Gotz et al., GCN 32660; Frederiks et al., GCN 32668) with Sintez-Newton 350mm f/5 telescope equipped with QHY600M camera and g'r'i'z' filters. Observation started on 2022-10-10 (UT) 17:24:54. The series consists of images with an exposure of 120 s in r'-filter. In the stacked image we clearly detect the optical afterglow (e.g. Dichiara et al., GCN 32632; Lipunov et al., GCN 32634; Perley GCN 32638; Hu et al., GCN 32644; Belkin et al., GCN 32645; Kuin et al., GCN 32656; Kim et al., GCN 32670). Preliminary photometry of the afterglow is following Preliminary photometry of the stacked images is following Date UT start t-T0 Filter Exp. OT err UL(3) (mid, days) (s) 2022-10-10 17:24:54 1.16293 r' 40*120 18.43 0.10 20.9 The photometry is based on nearby PS1 stars