TITLE: GCN CIRCULAR NUMBER: 45221 SUBJECT: Fermi GRB 260726A: Global MASTER-Net observations report DATE: 26/07/27 01:46:31 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), M. Segura, 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-SAAO robotic telescope [1] located in South Africa (South African Astronomical Observatory) started inspect of the Fermi GRB 260726A ( Fermi GBM team, GCN 45218) errorbox 3746 sec after notice time and 3782 sec after trigger time at 2026-07-27 00:47:51 UT, with upper limit up to 17.5 mag. The observations began at zenith distance = 78 deg. The sun altitude is -59.0 deg. The galactic latitude b = -10 deg., longitude l = 127 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3444915 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 3812 | 2026-07-27 00:47:51 | MASTER-SAAO | (00h 33m 08.03s , +40d 42m 54.8s) | C | 60 | 17.4 | 4815 | 2026-07-27 01:04:33 | MASTER-SAAO | (00h 53m 12.92s , +40d 41m 37.6s) | C | 60 | 17.4 | 4915 | 2026-07-27 01:06:13 | MASTER-SAAO | (01h 11m 16.44s , +38d 48m 24.2s) | C | 60 | 17.1 | 5018 | 2026-07-27 01:07:57 | MASTER-SAAO | (00h 34m 12.82s , +42d 36m 13.8s) | C | 60 | 17.4 | 5327 | 2026-07-27 01:13:06 | MASTER-SAAO | (00h 14m 01.29s , +44d 30m 13.1s) | C | 60 | 17.3 | 5926 | 2026-07-27 01:23:05 | MASTER-SAAO | (01h 13m 23.75s , +40d 41m 40.4s) | C | 60 | 17.1 | 6024 | 2026-07-27 01:24:42 | MASTER-SAAO | (01h 30m 51.35s , +38d 49m 10.7s) | C | 60 | 16.9 | 6121 | 2026-07-27 01:26:19 | MASTER-SAAO | (00h 54m 59.03s , +42d 36m 51.3s) | C | 60 | 17.5 | 6426 | 2026-07-27 01:31:24 | MASTER-SAAO | (00h 35m 31.56s , +44d 32m 11.3s) | C | 60 | 17.3 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. [1] - V.M. Lipunov, V.G. Kornilov, E.S. Gorbovskoy, N.A. Tiurina & A.S.Kuznetsov, 2023, Astronomical Robotic Networks and Operative Multichanel Astrophysics, Lomonosov MSU PRESS, 591pp. http : // www.pereplet.ru/lipunov/625.html View this GCN Circular online at https://gcn.nasa.gov/circulars/45221. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...