TITLE: GCN CIRCULAR NUMBER: 41547 SUBJECT: Fermi trigger No 777883624: Global MASTER-Net observations report DATE: 25/08/26 08:30:49 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru> V.Lipunov, E.Gorbovskoy, A.Kuznetsov, K.Zhirkov, I.Panchenko, N.Tiurina, P.Balanutsa, V.Topolev, D.Vlasenko, G.Antipov, A.Sankovich, Yu.Tselik, Ya.Kechin, V.Senik, A.Chasovnikov, K.Labsina, I. Gorbunov (Lomonosov MSU), O.Gress, N.Budnev (ISU), C.Francile, F. Podesta, R.Podesta, E. Gonzalez (Observatorio Astronomico Felix Aguilar (OAFA), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A.Sosnovskij (CrAO), 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) started inspect of the Fermi GRB250826.28 (trigger No 777883624,23h 40m 02.40s , -64d 12m 00.0s, R=4.94) errorbox 90 sec after notice time and 132 sec after trigger time at 2025-08-26 06:49:11 UT, with upper limit up to 20.3 mag. The observations began at zenith distance = 34 deg. The sun altitude is -53.0 deg. The galactic latitude b = -52 deg., longitude l = 315 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2977396 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 147 | 2025-08-26 06:49:11 | MASTER-OAFA | (23h 39m 27.05s , -64d 23m 49.4s) | C | 30 | 19.9 | 183 | 2025-08-26 06:49:47 | MASTER-OAFA | (23h 39m 27.12s , -64d 23m 50.0s) | C | 30 | 19.9 | 224 | 2025-08-26 06:50:23 | MASTER-OAFA | (23h 39m 27.23s , -64d 23m 50.4s) | C | 40 | 19.9 | 275 | 2025-08-26 06:51:09 | MASTER-OAFA | (23h 39m 27.37s , -64d 23m 50.7s) | C | 50 | 19.9 | 336 | 2025-08-26 06:52:05 | MASTER-OAFA | (23h 39m 27.59s , -64d 23m 50.9s) | C | 60 | 20.3 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. View this GCN Circular online at https://gcn.nasa.gov/circulars/41547. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...