TITLE: GCN CIRCULAR NUMBER: 23025 SUBJECT: GRB 180723.76: MASTER optical observation of the bright long Fermi GBM trigger number 554062193 DATE: 18/07/24 08:17:49 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs E. Gorbovskoy, V.Lipunov, N.Tiurina, V.Kornilov, A.Kuznetsov, V.Chazov, I. Gorbunov, D.Zimnukhov, D.Kuvshinov, P.Balanutsa, V.Vladimirov, D.Vlasenko, Lomonosov Moscow State University,SAI D.Svinkin Ioffe Institute, Sankt Petersburg D. Buckley, South African Astronomical Observatory (SAAO) R. Rebolo, M. Serra, N. Lodieu, G. Israelian, L. Suarez-Andres The Instituto de Astrofisica de Canarias (IAC) 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) O. Gres, N.M.Budnev , Yu.Ishmuhametova Irkutsk State University (ISU) A. Gabovich, V. Yurkov, Yu. Sergienko Blagoveschensk Educational State University (BSPU) MASTER-SAAO robotic telescope (MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in South Africa (South African Astronomical Observatory) was pointed to the GRB180723.76 198 sec after notice time and 767 sec after trigger time at 2018-07-23 18:22:35 UT (see Fermi GBM trgger number 554062193). On our first (150s exposure) set we haven`t found optical transient within FERMI error-box (ra=7.83333 dec=-66.1097 r=1). The 5-sigma upper limit has been about 17.5 mag There is no OT brighter 19.2 mag found on stacked images. The coverage map of the 3 sigms + sigma error box is available at http://master.sai.msu.ru/static/OT/MASTERSAAOmapFermi554062193.jpg The observations made on zenit distance = 74 degrees under strong wind, galaxy latitude b = -51 degree. The moon (86 % bright part) is 69 degrees above the horizon. The distance between moon and object is 82 The sun altitude is -31.3 degree. The object observed till sunrise at 2018-07-24 05:30:53 UT. The message may be cited.