TITLE: GCN CIRCULAR NUMBER: 22430 SUBJECT: GRB 180205A: Mondy optical observations DATE: 18/02/21 16:55:22 GMT FROM: Alexei Pozanenko at IKI, Moscow E. Mazaeva (IKI), A. Volnova (IKI), A. Pozanenko (IKI), E. Klunko (ISTP) report on behalf of of larger GRB follow-up collaboration: We observed the field of GRB 180205A (Evans et al., GCN 22381) with AZT-33IK telescope of Sayan observatory (Mondy). We obtained several images in R and B-filter on Feb. 05 - Feb. 19. The afterglow of GRB 180205A (Evans et al., GCN 22381; Zheng et al. GCN 22382; Bolmer et al. GCN 22383;Tanvir et al. GCN 22384; Volnova et al. GCN 22387; Falcon et al. GCN 22380; Xin et al. GCN 22392; Zhu et al. GCN 22395; Emery et al. GCN 22396; Im et al., GCN 22397; Oksanen et al. 22401; Mazaeva et al., GCN 22403; Volnova et al., GCN 22411; Cunningham et al., GCN 22414) is detected in stacked images. Preliminary photometry is following. Date UT start t-T0 Filter Exp. OT Err. UL (mid, days) (s) 2018-02-05 15:21:12 0.49438 R 30*120 19.32 0.04 21.9 2018-02-05 16:23:51 0.53094 B 20*120 20.70 0.17 21.3 2018-02-05 20:03:02 0.69011 R 60*60 19.60 0.08 21.7 2018-02-06 16:07:42 1.50850 R 30*120 20.25 0.07 22.0 2018-02-14 15:48:28 9.50557 R 45*120 22.46 0.13 23.9 2018-02-18 13:23:22 13.40481 R 45*120 n/d n/d 23.0 2018-02-19 14:37:56 14.45658 R 45*120 23.6 0.3 23.6 The photometry is based on nearby SDSS DR9 stars SDSS_id R_Lupton J082719.98+113324.0 16.206 0.013 J082717.26+113400.0 16.092 0.013 J082715.06+113230.6 15.553 0.013