TITLE: GCN CIRCULAR NUMBER: 27446 SUBJECT: GRB 200325B: MASTERt OT detection DATE: 20/03/26 12:13:10 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, P.Balanutsa,A.Kuznetsov,F.Balakin, V.Vladimirov, D. Vlasenko, I.Gorbunov, D.Zimnukhov, V.Senik, T.Pogrosheva, D.Kuvshinov(Lomonosov Moscow State University, SAI, Physics Department), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), R. Podesta, C.Lopez, F. Podesta, C.Francile(Observatorio Astronomico Felix Aguilar OAFA), H.Levato(Instituto de Ciencias Astronomicas, de la Tierra y del Espacio ICATE), R. Rebolo, M. Serra(The Instituto de Astrofisica de Canarias), D. Buckley(South African Astronomical Observatory), O.A. Gres, N.M. Budnev, O.Ershova (Irkutsk State University, API), V. Yurkov, A. Gabovich, Yu. Sergienko(Blagoveschensk Educational State University) MASTER OT J111012.51+274912.8 discovery - new OT inside Fermi GRB 200325B (trigger 606840801) MASTER Global Robotic Net inspected GRB 200325B: Fermi trigger 606840801, Ttr=2020-03-05 14:53:16 UT, GCN #27441, MASTER report GCN #27442, MASTER map and OT position. During inspection MASTER-Kislovodsk auto-detection system ( Lipunov et al., "MASTER Global Robotic Net", Advances in Astronomy, 2010, 30L ) discovered new OT source at (RA, Dec) = 11h 10m 12.51s +27d 49m 12.8s on 2020-03-25 16:21:15 UT. The OT unfiltered magnitude is 16.1m (mlim=17.8). The OT is seen in 2 inspect images (MASTER has 2 tubes at each observatory and works with large error-fields like Fermi in open mode, that gives 8 square degrees, i.e. 2x4sq.deg.). There is no minor planet at this place and no any sources in VIZIER database (22mag limit in POSS history). We have reference images on 2010-03-13.87244 UT with unfiltered mlim= 20.2m, on 2020-02-21 21:54:40UT with mlim=20.3. Spectral observations are required. The discovery and reference images are available at: http://master.sai.msu.ru/static/OT/111012.51274912.8.png