TITLE: GCN CIRCULAR NUMBER: 19976 SUBJECT: GRB 161001A: MASTER-OAFA and MASTER-SAAO early optical observations DATE: 16/10/02 10:08:33 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs R.Podesta, C.Lopez, F. Podesta Observatorio Astronomico Felix Aguilar (OAFA) H. Levato, C. Saffe Instituto de Ciencias Astronomicas, de la Tierra y del Espacio (ICATE) D.Buckley, S. Potter, South African Astronomical Observatory E.Gorbovskoy, V. Lipunov, N.Tyurina, V.Kornilov, O.Gress, P.Balanutsa, A.Kuznetsov, D.Kuvshinov Lomonosov Moscow State University, Sternberg Astronomical Institute R. Rebolo, M. Serra Ricart, N. Lodieu, G. Israelian The Instituto de Astrofisica de Canarias K.Ivanov, J.Rabinovich, N.M.Budnev, Irkutsk State University A. Tlatov, V.Senik, D. Dormidontov, A.Parkhomenko Kislovodsk Solar Station of the Pulkovo Observatory V.Yurkov, Yu.Sergienko, A.Gabovich Blagoveschensk Educational State University, Blagoveschensk MASTER-OAFA robotic telescope (MASTER-Net: http://observ.pereplet.ru) located in OAFA was pointed to the GRB161001A 29 sec after notice time and 41 sec after trigger time at 2016-10-01 01:05:57UT. On our first (10s exposure) set we not found OT within 6 square degrees field around SWIFT BAT error-box (Page et al., GCN 19967; Markwardt et al.,GCN 19974 ) brighter then 16.7 unfiltered magnitude. MASTER-SAAO robotic telescope (MASTER-Net: http://observ.pereplet.ru) located in SAAO was pointed to the GRB161001A 167 sec after notice time and 176 sec after trigger time at 2016-10-01 01:08:17 UT. On our first (40s exposure) set we haven`t found optical transient within SWIFT error-box. The 5-sigma upper limit has been about 18.4 mag We found optical object at first hour coadded images by both MASTERs telescopes at coordinates Ra 04:47:40.83 Dec -57:15:38.07 (+-0.7 arcsec error) with unfiltered magnitude: 0.8R +0.2B = 20.6 (+0.1 -0.4) with respect to USNO B stars. We have archival images in MASTER SAAO DataBase at 2016-04-09 with 20.9 3-SIGMA limit. We see same object at same position. We note that our scale is 1 pix ~ 2 arcsec . So the DSS2 object (Kruehler et al., GCN 19971) and GROND afterglow candidate (Chen et al., GCN 19975) are inside the our pixel. The message may be cited.