TITLE: GCN CIRCULAR NUMBER: 22226 SUBJECT: GRB 171205A: MASTER-Net OT recent photometry DATE: 17/12/10 17:15:00 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, D.Kuvshinov, A.V.Krylov, I.Gorbunov, P.Balanutsa, A.Kuznetsov, V.V.Chazov, D. Vlasenko Lomonosov Moscow State University, Sternberg Astronomical Institut of MSU R.Podesta, C.Lopez, F. Podesta Observatorio Astronomico Felix Aguilar (OAFA), National University of San Juan, Argentina H. Levato, C. Saffe Instituto de Ciencias Astronomicas,de la Tierra y del Espacio (ICATE), San Juan, Argentina D.Buckley, S. Potter, A.Kniazev, M.Kotze South African Astronomical Observatory R. Rebolo, M. Serra, N. Lodieu, G. Israelian, L. Suarez-Andres The Instituto de Astrofisica de Canarias O.Gres, K.Ivanov, S.Yazev, N.M.Budnev, O.Gres, O.Chuvalaev, V.A.Poleshchuk, Irkutsk State University V.Yurkov, Yu.Sergienko Blagoveschensk Educational State University, Blagoveschensk A. Tlatov, V.Senik, A.V. Parhomenko, D. Dormidontov Kislovodsk Solar Station of the Pulkovo Observatory MASTER Global Robotic Net (http://observ.pereplet.ru) observes Swift GRB 171205A (D'Elia et al., GCN 22177) every night at MASTER-Kislovodsk, MASTER-IAC, MASTER-SAAO . The optical counterpart (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; Postigo et al. GCN 22204) preliminary photometry of last nights is the following Date UT Filter OT 2017-12-09 00:40:04.45 B 18.6+-0.2 2017-12-09 01:41:23.53 B 18.5+-0.2 2017-12-10 04:42:29.82 B 18.2+-0.2 2017-12-10 05:50:48.67 V 17.20+-0.20 2017-12-10 06:11:24.21 B 17.80+-0.24 2017-12-10 06:22:41.40 B 17.68+-0.16 2017-12-10 06:22:41.40 B 17.32+-0.19 This message can be cited.