TITLE: GCN CIRCULAR NUMBER: 24737 SUBJECT: S190602aq: MASTER OT detection DATE: 19/06/04 07:32:42 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V. Lipunov, V.Kornilov, E.Gorbovskoy, N.Tiurina, A.Kuznetsov, I.Gorbunov, V.Vladimirov, P.Balanutsa, D.Vlasenko, D.Zimnukhov, F.Balakin,A. Chasovnikov, V.Topolev, V.Senik, D.Kuvshinov(Lomonosov Moscow State University, SAI, Physics Department), D. Buckley (South African Astronomical Observatory), 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), O. Gress, N.M. Budnev, O.Ershova, S.Yazev (Applied Physics Institute, Irkutsk State University), V. Yurkov, A. Gabovich, Yu. Sergienko, D. Kobcev (Blagoveschensk Educational State University), A. Tlatov, D.Dormidontov, A.V. Parhomenko (Kislovodsk Solar Station of the Pulkovo Observatory), MASTER Global Robotic Net (Lipunov et al., 2010, Advances in Astronomy,vol.2010, 30L (http://observ.pereplet.ru) MASTER Global Robotic Net inspected S190602aq (Shawhan et al. GCN #24717, Lipunov et al. GCN #24721) and discovered optical transient (may be or not connected with BBH merging) MASTER OT J120315.71-525727.2 (ATel #12834; AT 2019gtv https://wis-tns.weizmann.ac.il/object/2019gtv) discovery- PSN in 1.1"E,6.3"S of PGC3074107 MASTER-OAFA auto-detection system ( Lipunov et al., "MASTER Global Robotic Net", Advances in Astronomy, 2010, 30L ) discovered OT source at (RA, Dec) = 12h 3m 15.71s -52d 57m 27.20s on 2019-06-03 01:34:01UT. The OT unfiltered magnitude is m=16.9 (mlim=18.6m). The OT is seen in 2 inspect images. We reobserved it at MASTER-SAAO at 2019-06-03 16:39:45UT with m_OT=16.7. We have reference image without OT on 2019-04-24 22:43:07 UT with unfiltered mlim=18.6 m. This PSN is in 1.1"E,6.3"S of PGC3074107 (with unknown z, and magnitude http://leda.univ-lyon1.fr/ledacat.cgi?PGC3074107). Spectral observations are required. The discovery and reference images are available at: http://master.sai.msu.ru/static/OT/MASTEROTJ120315.71-525727.2.jpg