TITLE: GCN CIRCULAR NUMBER: 22874 SUBJECT: GRB 180626C / Fermi trigger 551697835: MASTER inspection DATE: 18/06/30 16:18:31 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tiurina, A.Kuznetsov, V.Chazov, I. Gorbunov, D. Vlasenko, D.Zimnukhov, D.Kuvshinov, P.Balanutsa, V.Vladimirov Lomonosov Moscow State University,SAI R. Rebolo, M. Serra, N. Lodieu, G. Israelian, L. Suarez-Andres The Instituto de Astrofisica de Canarias A. Tlatov, V.Senik, D. Dormidontov Kislovodsk Solar Station of the Pulkovo Observatory R. Podesta, F. Podesta, C. Lopez, C.Francile Observatorio Astronomico Felix Aguilar (OAFA) H.Levato, Instituto de Ciencias Astronomicas, de la Tierra y del Espacio (ICATE) D. Buckley South African Astronomical Observatory O. Gres, N.M.Budnev , Yu.Ishmuhametova Irkutsk State University A. Gabovich, V. Yurkov, Yu. Sergienko Blagoveschensk Educational State University, Blagoveschensk MASTER-IAC robotic telescope (MASTER-Net: http://observ.pereplet.ru Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) , located in Teyde Observatory (IAC, Spain), was pointed to the IPN (Svinkin et al. GCN22864, Kozlova et al. GCN22868) Triangulation GRB180626C / Fermi trigger 551697835 (GRB_Time 18/06/26 09:23:50.65UT; RA,Dec(2000)=19h 00m 14s +44d 49' 12" (GRB_ERROR: 8.21 deg radius, statistical only , see https://gcn.gsfc.nasa.gov/other/551697835.fermi) also inspected by ZTF (Coughlin et al. GCN22871) at 2018-06-26 21:37:30UT-22:53:48 with unfiltered mlim=19.1 (180s expositions); 2018-06-27 03:34:57-03:53:20 with mlim=19.7 on summary expositions (5sigma, exp=540s). The observations started on zenit distance = 41 degrees. The sun altitude was -17.66 degree. MASTER-SAAO robotic telescope located in South Africa started Fermi inspection 5834 sec after notice time and 37433 sec after trigger time at 2018-06-26 19:51:28 UT. The 5-sigma upper limit on our second (180s exposure) set is about 16.2mag. The observations started on zenit distance = 89 degrees, galaxy latitude b = 22 degree. The moon (98 % bright part) is 64 degrees above the horizon. The distance between moon and object is 69. The sun altitude was -52.2 degree. MASTER-Amur robotic telescope, located at BSPU, was pointed to Fermi trigger 551697835 on 2018-06-27 14:09:39UT, and observed till 14:57:32.584UT with mlim=18.0(180s exp) MASTER-Kislovodsk robotic telescope, located at Kislovodsk Solar Station of Pulkovo observatory, started Fermi trigger inspection at 2018-06-27 20:53:26 UT. The 5-sigma upper limit on our first (180s exposure) set is about 18.8mag . The observations started on zenit distance = 6 degrees, galaxy latitude b = 22 degree. The moon (100 % bright part) is 26 degrees above the horizon. The distance between moon and object is 68 .The sun altitude is -22.8 degree. New OT, that could be connected with GRB, wasn't found.