TITLE: GCN CIRCULAR NUMBER: 22397 SUBJECT: GRB 180205A: Optical observations DATE: 18/02/06 14:45:44 GMT FROM: Myungshin Im at Seoul Nat U Myungshin Im, Changsu Choi, Gregory S. Paek, Sung A O, Sophia Kim (CEOU/SNU), Yuji Urata (NCU), H.-I. Sung (KASI) on behalf of a larger collaboration We observed 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. 22392; Zhu et al. 22395; Emery et al. 22396) with the 1-m telescope at the Mt. Lemmon Optical Astronomy Observatory (LOAO) and the 0.8m and 0.25 telescopes at the McDonald Observatory. The observation started at about 1 hour after the initial alert, using B, V, R, I, z, and Y filters. The observation continued throughout the night. We clearly identify the optical afterglow in these bands, and ​a ​ preliminary photometry in R-band shows R ~ 18 mag at 1.3 hours post-burst. Further observations and analysis are being carried out ​, including telescopes in Korea​ . Additional ​results ​ will be reported ​ as they become available​ .