TITLE: GCN CIRCULAR NUMBER: 41806 SUBJECT: GRB 250911A: MASTER optical counterpart observations DATE: 25/09/12 00:53:31 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru> V.M.Lipunov (Lomonosov MSU, Moscow), C.Francile, F. Podesta, R.Podesta, E. Gonzalez (OAFA), A.Kuznetsov, A.Sankovich, G.Antipov, P.Balanutsa, E.Gorbovskoy, N.Tiurina, M.Shilova, A.Chasovnikov, V.Topolev, K.Zhirkov, Ya.Kechin, V.Senik, D.Vlasenko (Lomonosov MSU), D.Buckley, (SAAO, South Africa) O.Gress, N.Budnev (ISU, Irkutsk), A.Sosnovskij (Crao RAS), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity), V.M.Pillet, R.Rebolo Lopez (The Instituto de Astrofisica de Canarias, Spain), L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez,J.Martinez,A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysic Observatory, Mexico) MASTER-OAFA robotic telescope (Global MASTER-Net: http://observ.pereplet.ru,Argentina started Swift GRB 250911A (Klingler et al. GCN 41781) observations automatically at 2025-09-11 02:25:44UT and in own planner mode befor it. There is GRB optical counterpart MASTER OT J173500.02-165114.40 with mOT~18.81 at Swift position (XRT Perri et al. GCN 41783, Beardmore et al. GCN 41784, Dichiara et al. GCN 41804; UVOT Siegel et al. GCN 41800), first reported by COLIBRI (Angula et al. GCN 41782). All images reduction will be continued. The message may be cited. References 1) Lipunov et al. 2010, MASTER Robotic Net, Advances in Astronomy, vol. 2010, p.30L 2) Lipunov,V.G. Kornilov, E.S. Gorbovskoy, N.V. Tyurina, A.S. Kuznetsov, "ASTRONOMICAL ROBOTIC NETWORKS and OPERATIVE MULTICHANNEL ASTROPHYSICS. Based on the example of the global MASTER network.", The Moscow State University Publishing House. In the series "Works of Outstanding Scientists of Moscow State University", http://www.pereplet.ru/lipunov/625.html#625) View this GCN Circular online at https://gcn.nasa.gov/circulars/41806. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...