TITLE: GCN CIRCULAR NUMBER: 24680 SUBJECT: GRB 190530A: MASTER OT detection DATE: 19/05/30 19:03:26 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V. Lipunov (Lomonosov MSU), D.Svinkin (Ioffe Institute), O.Gress, A.Kuznetsov, N.Tyurina, V.Kornilov, D.Vlasenko, V.Vladimirov, D.Zimnukhov, P.Balanutsa, F.Balakin, E. Gorbovskoy, A. Chasovnikov, V.Topolev, D.Kuvshinov (Lomonosov Moscow State University, SAI, Physics Department), R. Podesta, C. Lopez, C.Francile, F. Podesta (Observatorio Astronomico Felix Aguilar OAFA, San Juan National University), H.Levato (Instituto de Ciencias Astronomicas, de la Tierra y del Espacio ICATE, SJNU) R. Rebolo, M. Serra, N. Lodieu, G. Israelian, L. Suarez-Andres (The Instituto de Astrofisica de Canarias), D. Buckley (South African Astronomical Observatory), O. Gress, N.M. Budnev, O.Ershova, Yu.Ishmuhametova, S.Yazev (Applied Physics Institute, Irkutsk State University), V. Yurkov, A. Gabovich, Yu. Sergienko, D. Kobcev (Blagoveschensk Educational State University), A. Tlatov, V.Senik, A.V. Parhomenko, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), MASTER-Kislovodsk robotic telescope (MASTER Global Robotic Net http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy,vol. 2010, 30L) automatically was pointed to the GRB190530A Fermi LAT localization (Longo et al GCN 24679) (also inspected BALROG localization Biltzinger et al. GCN 24677 and Fermi team error-box GCN 24676) at 2019-05-30 18:12:10 (sun altitute= -16deg., alert_altitute=23deg.) We detect MASTER OT J080207.73+352847.7 (RA,Dec2000)=08h 02m 07.73s +35d 28m 47.7s with m_OT=16.7m (but in 3.8" there is optical source at PANSTARRs images with rmag=20.9, gmag=22.6) OT is inside Barlog error box (GCN 24677). The covered map and OT place is available at https://master.sai.msu.ru/site/master2/event.php?id=1034468 Observation and reduction will be continued. The message may be cited.