TITLE: GCN CIRCULAR NUMBER: 24076 SUBJECT: LIGO/Virgo S190408an: MASTER OT detection DATE: 19/04/09 07:58:43 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V. Lipunov, T.Pogrosheva, E. Gorbovskoy, N.Tyurina, V.Kornilov, D.Vlasenko, V.Vladimirov, D.Zimnukhov, A.Kuznetsov, P.Balanutsa, I.Gorbunov, A. Chasovnikov, V.Grinshpun, F.Balakin (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 (Applied Physics Institute, Irkutsk State University), V. Yurkov, A. Gabovich, Yu. Sergienko, D. Kobcev (Blagoveschensk EducationState University), A. Tlatov, V.Senik, A.V. Parhomenko, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), MASTER Global Robotic Net (http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy,vol. 2010, 30L) during LIGO/Virgo S190408an (Singer et al. GCN 24069) South Part Error Field Inspection (Lipunov et al. GCN 24070) at MASTER-OAFA found optical transient (no known sources in VIZIER database inside 5") MASTER OT J140518.22-395309.9 discovery MASTER auto-detection system discovered OT source at (RA,Dec2000) = 14h 05m 18.22s -39d 53m 09.9s on 2019-04-09.07809UT. The OT unfiltered magnitude is 17.4m (mlim=19.1m). The OT is seen in 2 MASTER LVC inspect images (Pogrosheva et a., ATel #12644). There is no minor planet at this place. We have reference image without OT on 2018-05-19.13417 UT with 20.2 unfiltered magnitude limit. There is no any sources in VIZIER database. Spectral observations are required. The discovery and reference images are available at: http://master.sai.msu.ru/static/OT/140518.22-395309.9.png MASTER cover map of Ligo/Virgo S190408an error-field inspection will be available on-line at: http://master.sai.msu.ru/static/LVC/MASTER_S190408an_map.jpg Reduction and observation will be cntinued. The message may be cited.