TITLE: GCN CIRCULAR NUMBER: 15792 SUBJECT: GRB 140206A: ISON-Ussuriysk optical observations DATE: 14/02/06 15:54:46 GMT FROM: Alexei Pozanenko at IKI, Moscow A. Volnova (IKI), A. Stepura (UAFO, ISON), A. Matkin (UAFO, ISON), I. Molotov (KIAM), A. Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration: We observed the afterglow (Oksanen et al., GCN 15786; Oate et al., GCN 15787) of the Swift and INTEGRAL GRB 140206A (Lien et al., GCN 15784; Gotz et al., GCN 15785) with VT-50 (0.5m) telescope of UAFO/ISON-Ussuriysk observatory starting on Feb. 6 (UT) 09:20:05, i.e. ~2 hours after burst trigger. We took unfiltered images of 30s exposures. In stacked frames we clearly detect afterglow. A preliminary photometry of the afterglow is following: T_start T0+ Filter, Exposure, OT, OT_err (UT) (mid, d) (s) 2014-02-06T09:20:39 0.08783 none 9*30 17.76 0.24 2014-02-06T10:52:26 0.15309 none 19*30 18.06 0.08 The photometry is based on reference stars SDSS-DR9, (R mag, transformation by Lupton 2005) N SDSS_id R(Lupton)errR 1 J094123.75+664429.9 15.441+/-0.013 2 J094126.54+664410.8 13.837+/-0.014 3 J094131.29+664857.0 13.972+/-0.011 Observations continuing. The finding chart can be found in http://grb.rssi.ru/GRB140206A/grb140206A_VT50_fc.png