TITLE:   GCN CIRCULAR
NUMBER:  41558
SUBJECT: EP250827a / GRB 250827A: MASTER-OAFA OT observation
DATE:    25/08/27 10:09:42 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>

V.Lipunov, A.Kuznetsov, I.Panchenko, G.Antipov, P.Balanutsa, K.Zhirkov (Lomonosov MSU), C.Francile,  F. Podesta, R.Podesta, E. Gonzalez (OAFA),
A.Chasovnikov, E.Gorbovskoy, N.Tiurina, Ya.Kechin, D.Vlasenko, V.Senik, M. Shilova, I.Lipunov, V.Topolev (Lomonosov MSU), O.Gress, N.Budnev(ISU),
D.Buckley (SAAO),
A.Sosnovskij (Crao RAS),
A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory),
R.Rebolo (The Instituto de Astrofisica de Canarias),
L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez,J.Martinez,A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro  AstrophysicsObservatory
A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity)

MASTER-OAFA robotic telescope (Lipunov et al. GCN 41556)
started EP GRB 250827A observation at 2025-08-27 07:46:54 UT
and detected optical couterpart of this GRB
MASTER OT J001352.27-562952.8 with m_OT (unfiltered) = 18.9m (preliminary) at 2025-08-27 07:48:10 https://master.sai.msu.ru/site/master2/event.php?id=2978010 The light curve demonstrates multipeak structure from 18 to 19 during last hour.

This OT coincide with GEMINI-South detection ( GCN 41554 Levan et al.) and Las Cumbres one (GCN 41555 Wenxiong Li et al.)