TITLE: GCN CIRCULAR NUMBER: 30518 SUBJECT: GRB 210724A: Zeiss-1000 of Koshka observatory, optical upper limit DATE: 21/07/26 12:14:12 GMT FROM: Alexei Pozanenko at IKI, Moscow S. Belkin (IKI), A. Novichonok (Petrozavodsk State University, KIAM), A. Pozanenko (IKI), A. Zhornichenko (KIAM), N. Pankov (HSE) report on behalf of IKI GRB FuN: We observed the field of GRB 210724A (D'Avanzo et al. GCN 30497) with Zeiss-1000 telescope of Koshka observatory starting on July 24 (UT) 20:39:32. We do not detect any object XRT error circle (D'Avanzo et al. GCN 30497). We also not detect the object at the position of the afterglow candidate (Ugarte Postigo et al., GCN 30511). Preliminary photometry of the field is following Date UT start t-T0 Filter Exp. OT Err. UL(3sigma) (mid, days) (s) 2021-07-24 20:39:32 0.024919 R 21*60 n/d n/d 18.6 The photometry is based on the nearby USNO-B1.0 stars USNO-B1.0_id R2 USNO-B1.0_id R2 0837-0267865 15.24 0836-0268753 16.95 0837-0267827 15.54