GRB 210610A: Maidanak and AbAO optical observations

We observed the field of GRB 210610A (Page et al., GCN 30160) with AZT-22 telescope of Maidanak Observatory and AS-32 telescope of Abastumani observatory (AbAO). The optical afterglow (Page et al., GCN 30160; Hosokawa et al., GCN 30161; Xu et a., GCN 30162; Kumar et al., GCN 30163; Lipunov et al., GCN 30166; de Wet et al., GCN 30168; Hosokawa et al., GCN 30169; Sun et al., GCN 30185; Watson et al., GCN 30191; Zheng et al., GCN 30203; Kann et al., GCN 30211; Belkin et al., GCN 30214; Moskvitin et al., GCN 30229; Kann et al., GCN 30232; Siegel et al., GCN 30246) is clearly detected in the stacked images. Preliminary photometry of the afterglow is following. Date UT start t-T0 Filter Exp. OT UL(3sigma) Telescope (mid, days) (s) 2021-06-10 17:57:56 0.14529 R 14*300 19.62 0.03 24.0 AZT-22 2021-06-10 20:24:59 0.23769 R 42*60 20.46 0.25 20.6 AS-32 2021-06-12 16:34:08 2.07494 R 7*300 23.09 0.20 23.5 AZT-22 2021-06-13 16:44:01 3.09049 R 12*300 23.77 0.21 24.4 AZT-22 2021-06-14 17:25:22 4.11920 R 12*300 24.08 0.28 24.4 AZT-22 Photometry is based on the SDSS-DR12 nearby stars (Lupton transformations). SDSS-DR12_id RA DEC R(Lupton) J133717.13+142854.9 204.32139900 +14.48192200 17.0295 J133703.62+142832.7 204.26512000 +14.47576300 17.7239 Using our data in the R filter, it was found that the light curve can be described by a broken power-law with power law indices of -0.82 and -1.39. The break time is 0.23+/-0.17 days. These values are consistent with the result reported by Kann et al. (GCN 30211). The light curve can be found at http://grb.rssi.ru/GRB210610A/GRB210610A_LC.png