TITLE: GCN CIRCULAR NUMBER: 21054 SUBJECT: Short GRB 170428A: MASTER-OAFA final reduction of the optical observations DATE: 17/05/01 11:13:25 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 K.Ivanov, S.Yazev, N.M.Budnev, O.Gres, O.Chuvalaev, V.A.Poleshchuk, O. Ershova 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 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 MASTER II robotic telescope (MASTER-Net: http://observ.pereplet.ru) located in OAFA was pointed to the GRB170428A (Beardmore et al., GCN 21042) 17 sec after notice time and 31 sec after trigger time at 2017-04-28 09:14:14 UT (Podesta et al., GCN 21044). Our unfiletred limits are: Date time Exp Proc.type Lim. (s) 2017-04-28 09:14:14 10 Alert (SWIFT) 16.6 2017-04-28 09:15:04 20 Alert (SWIFT) 17.1 2017-04-28 09:16:07 30 Alert (SWIFT) 17.6 2017-04-28 09:17:19 40 Alert (SWIFT) 17.9 2017-04-28 09:18:42 60 Alert (SWIFT) 18.2 2017-04-28 09:20:24 80 Alert (SWIFT) 18.6 2017-04-28 09:17:19 180 SumAlert(SWIFT) 19.1 2017-04-28 09:22:28 110 Alert (SWIFT) 18.9 2017-04-28 09:24:59 140 Alert (SWIFT) 19.0 2017-04-28 09:28:01 170 Alert (SWIFT) 19.2 2017-04-28 09:22:28 420 SumAlert(SWIFT) 19.7 2017-04-28 09:31:33 180 Alert (SWIFT) 19.3 2017-04-28 09:35:16 180 Alert (SWIFT) 19.4 2017-04-28 09:38:59 180 Alert (SWIFT) 19.5 2017-04-28 09:31:33 540 SumAlert (SWIFT) 19.9 2017-04-28 09:42:42 180 Alert (SWIFT) 19.5 2017-04-28 09:48:50 180 Alert (SWIFT) 19.5 2017-04-28 09:55:02 180 Alert (SWIFT) 19.5 2017-04-28 09:42:42 540 SumAlert (SWIFT) 20.1 2017-04-28 09:58:46 180 Alert (SWIFT) 19.4 2017-04-28 10:02:26 180 Alert (SWIFT) 19.1 2017-04-28 10:06:07 180 Alert (SWIFT) 18.8 2017-04-28 09:58:46 540 SumAlert (SWIFT) 19.3 2017-04-28 10:09:49 180 Alert (SWIFT) 18.3 2017-04-28 09:31:33 1800 SumAlert (SWIFT) 20.3 2017-04-28 10:02:26 1440 SumAlert (SWIFT) 19.8 The message may be cited.