TITLE: GCN CIRCULAR NUMBER: 22237 SUBJECT: GRB 171209A: MASTER-Net optical observations DATE: 17/12/11 14:05:44 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs E. Gorbovskoy, V. Lipunov, 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 II robotic telescope (MASTER-Net: http://observ.pereplet.ru) located in OAFA was starting survey on the SWIFT GRB171209A error-box (LaPorte et al. GCN 22213) 44912 sec after notice time and 44965 sec after trigger time at 2017-12-10 03:15:41 UT. The 5-sigma upper limit on our single (180s exposure) set is about 19.4-m and 20.0-m on coadd (3x180 = 540s) image. We not see OT previously reported by Kuin et al. GCN 22221 , Guidorzi et al. GCN 22214 , Kong et al. GCN 22230. MASTER II robotic telescope (MASTER-Net: http://observ.pereplet.ru) located in SAAO was starting survey on the SWIFT GRB171209A 114607 sec (~ 32 hours) after trigger time at 2017-12-10 03:15:41 UT. The 5-sigma upper limit on our single (180s exposure) set is about 19.4-m and 20.5-m on coadd (10 x 180 = 1800 s) image. Here we also not see any OT. This message can be cited.