TITLE: GCN CIRCULAR NUMBER: 40222 SUBJECT: Swift GRB250424.29: Global MASTER-Net OT detection DATE: 25/04/24 07:06:22 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru> C.Francile, F. Podesta, R.Podesta, E. Gonzalez (Observatorio Astronomico Felix Aguilar (OAFA), V.Lipunov, E.Gorbovskoy, N.Tiurina, P.Balanutsa, D.Vlasenko, I.Panchenko, A.Kuznetsov, G.Antipov, A.Sankovich, A.Sosnovskij, Yu.Tselik, M.Gulyaev, Ya.Kechin, V.Senik, A.Chasovnikov, K.Labsina (Lomonosov MSU), O.Gress, N.Budnev(ISU), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity) D.Buckley (SAAO), 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 Astrophysics Observatory) MASTER-OAFA robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Argentina (OAFA observatory of San Juan National University) was pointed to the GRB250424.29 99 sec after notice time and 178 sec after trigger time at 2025-04-24 06:55:26 UT. On our first (40s exposure) set we found 1 optical transient within Swift error-box (ra=217.512 dec=-35.0214 r=0.05) brighter than 18.9. T-Tmid Date Time Expt. Ra Dec Mag ---------|---------------------|-------|-----------------|-----------------|------- 198 2025-04-24 06:55:26 40 (14h 29m 59.96s , -35d 01m 30.7s) 18.0 The 5-sigma upper limit has been about 18.9mag The message may be cited. View this GCN Circular online at https://gcn.nasa.gov/circulars/40222. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...