GRB221009A: optical afterglow measurements from Konkoly Observatory

We observed the field of the bright GRB221009A (Dichiara et al., GCN #32632, Veres et al., GCN #32636) with the RC80 robotic telescope at Piszkesteto Station of Konkoly Observatory on 2022 Oct 10.81 UT and Oct 12.85 UT, during inferior sky conditions. A series of 300 sec frames were collected through Sloan r'- and i' bands. The bright optical afterglow (Lipunov et al. GCN #32634; Perley et al. GCN #32638; Broens GCN #32640; Hu et al. GCN #32644; Belkin et al. GCN #32645; Wet et al. GCN #32646; Xu et al. GCN #32647; de Ugarte Postigo et al. GCN #32648; Odeh GCN #32649; Brivio et al. GCN #32652; Kuin et al. GCN #32656; Paek et al. GCN #32659; Kumar et al. GCN #32662; Romanov GCN #32664; Odeh GCN #32666; Chen et al. GCN #32667; Vidal et al. GCN #32669; Kim et al. GCN #32670; Groot et al. GCN #32678; Romanov GCN #32679; Castro-Tirado et al. GCN #32686; Watson et al. GCN #32692; Strausbaugh et al. GCN #32693; Butler et al. GCN #32705) was clearly detected on the stacked frames with the following magnitudes, calibrated via nearby PS1 stars: Date UT-middle t-T0(hr) Exp(s) r'(AB-mag) i'(AB-mag) 2022-10-10 19:26:51 30.16 600 18.74 (0.12) 17.50 (0.08) 2022-10-12 20:18:24 79.02 300 20.58 (0.70) 18.74 (0.18) These magnitudes are not corrected for galactic extinction.