TITLE: GCN CIRCULAR NUMBER: 33530 SUBJECT: GRB 230328B: Mondy, AbAO and Kitab optical observations DATE: 23/03/28 21:40:25 GMT FROM: Alexei Pozanenko at IKI, Moscow S. Belkin (IKI), R. Ya. Inasaridze (AbAO), E. Klunko (ISTP), A. Novichonok (Petrozavodsk State University, KIAM), A. Pozanenko (IKI), N. Pankov (HSE, IKI), D. Datashvili (AbAO), V. R. Ayvazian (AbAO), G. V. Kapanadze (AbAO) report on behalf of GRB IKI FuN: We observed the field of Swift GRB 230328B (Gropp et al. GCN 33527; Osborne et al. GCN 33529) till now with AZT-33IK telescope of Mondy observatory in R-filter, RC-36 telescope of Kitab observatory in Clear, AS-32 telescope of Abastumani observatory in R-filter. The optical afterglow (Gropp et al. GCN 33527; Pankov et al. GCN 33528) is detected in Mondy and Abastumani, and not detected in Kitab observatory. Preliminary photometry of a stacked images is following Date UT start t-T0 Filter Exp. OT Err. UL(3sigma) (mid, days) (s) 2023-03-28 16:19:20 0.062188 R 5*120 19.34 0.10 21.0 2023-03-28 16:37:07 0.042338 Clear 19*60 n/d n/d 17.6 2023-03-28 16:15:48 0.086725 R 104*60 19.50 0.10 21.2 The photometry is based on nearby USNO-B1.0 stars. Approximation of above photometry in R-filter and photometry reported early (GCN 33528) results in the power law index of -0.45 of slow decay LC of GRB 230328B.