TITLE: GCN CIRCULAR NUMBER: 22224 SUBJECT: GRB 171205A: Mondy optical observations DATE: 17/12/10 10:17:25 GMT FROM: Alexei Pozanenko at IKI, Moscow A. Volnova (IKI), A. Pozanenko (IKI), E. Klunko (ISTP), E. Mazaeva (IKI) report on behalf of of larger GRB follow-up collaboration: We observed the field of GRB 171205A (D'Elia et al., GCN 22177) with AZT-33IK telescope of Sayan observatory (Mondy). We took several images in R-filter under non-optimal weathe conditions on Dec. 08 and fair condiotns on Dec. 09. The afterglow of GRB 171205A (Izzo et al. GCN 22180; Emery et al. GCN 22181; Butler et al. GCN 22182; Mao et al. GCN 22186; Choi et al. GCN 22188; Melandri et al. GCN 22189; Steeghs et al. GCN 22190; Cobb et al. GCN 22192; Volnova et al. GCN 22193; Guidorzi et al. GCN 22197; Schmidl et al. GCN 22198; Lipunov et al. GCN 22199; Ugarte Postigo et al. GCN 22204) is detected on Dec. 09. Preliminary photometry is following. Date UT start t-T0 Filter Exp. OT Err. UL (mid, days) (s) 2017-12-08 21:18:28 3.59292 R 1200 n/d n/d 18.5 2017-12-09 20:44:55 4.57936 R 3300 18.4 0.1 21.7 The photometry is based on several nearby USNO-B1.0 stars previously used in GCN 22193.