TITLE: GCN CIRCULAR NUMBER: 27455 SUBJECT: GRB 200325B: Mondy, CrAO, AbAO afterglow confirmation and refined photometry of MASTER OT J111012.51+274912.8 DATE: 20/03/27 13:14:36 GMT FROM: Alexei Pozanenko at IKI, Moscow S. Belkin (IKI), A. Pozanenko (IKI), E. Klunko (ISTP), A. Sosnovskij (CrAO), R. Ya. Inasaridze (AbAO), V. Rumyantsev (CrAO), M. Eselevich (ISTP), E. Mazaeva (IKI), A. Volnova (IKI) report on behalf of IKI-GRB-FuN: We observed the MASTER OT J111012.51+274912.8 (Lipunov et al., GCN 27446) as a candidate in afterglow of the Fermi GRB 200325B (Fermi GBM team, GCN 27441) with AZT-33VM 1.5-m telescope of Sayan observatory (Mondy) starting on 2020-03-26 (UT) 15:08:10, ZTSh 2.6m telescope of CrAO starting on 2020-03-26 (UT) 20:11:20 (Pozanenko et al., GCN 27452), and AS-32 0.7m telescope of Abastumani observatory starting on 2020-03-26 (UT) 20:27:39. Below we present refined photometry of the OT. Preliminary photometry of the object is following. Date UT start t-T0 Filter Exp. OT Err UL(3sigma) telescope (mid, days) (s) 2020-03-26 15:08:10 1.0263 R 23*120 19.89 0.05 22.6 AZT-33VM 2020-03-26 20:11:20 1.2306 R 14*120 20.07 0.08 22.3 ZTSh 2020-03-26 20:27:39 1.2444 R 35*60 n/d n/d 20.0 AS-32 the photometry is based on nearby SDSS-DR12 stars RA DEC R(Lupton transformations) 167.569191 27.848262 16.015 167.513655 27.832992 16.930 167.510507 27.850424 15.261 We note that coordinates of the OT (Lipunov et al., GCN 27446; Pozanenko et al., GCN 27452) coincide with only one XRT source (https://www.swift.ac.uk/ToO_GRBs/00020978/ ) found in the error localization of GBM/Fermi. Taking into account the XRT source and fading OT we suggest the MASTER OT J111012.51+274912.8 is an afterglow GRB 200325B.