TITLE: GCN CIRCULAR NUMBER: 44788 SUBJECT: SVOM GRB260603.23: Global MASTER-Net observations report DATE: 26/06/03 06:30:40 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-OAGH robotic telescope [1] located in Mexico (OAGH National Institute for Astrophysics, Optics and Electronics) was pointed to the SVOM GRB260603.23 (trigger No 1780465035,15h 32m 48.05s , +40d 06m 06.5s, R=0.1222) errorbox 6 sec after notice time and 1357 sec after trigger time at 2026-06-03 05:59:52 UT, with upper limit up to 17.4 mag. The observations began at zenith distance = 9 deg. The sun altitude is -33.5 deg. MASTER-OAFA robotic telescope located in Argentina (OAFA observatory of San Juan National University) was pointed to the SVOM GRB260603.23 errorbox 241 sec after notice time and 1593 sec after trigger time at 2026-06-03 06:03:48 UT, with upper limit up to 16.4 mag. The observations began at zenith distance = 81 deg. The sun altitude is -67.9 deg. The galactic latitude b = 54 deg., longitude l = 64 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3357257 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 1418 | 2026-06-03 05:59:52 | MASTER-OAGH | (15h 33m 43.57s , +40d 02m 45.7s) | P- | 120 | 16.8 | 1546 | 2026-06-03 06:02:01 | MASTER-OAGH | (15h 33m 43.89s , +40d 01m 28.2s) | P- | 120 | 17.1 | 1624 | 2026-06-03 06:03:48 | MASTER-OAFA | (15h 32m 34.31s , +40d 16m 14.5s) | C | 60 | 15.8 | 1684 | 2026-06-03 06:03:48 | MASTER-OAFA | (15h 32m 34.31s , +40d 16m 14.2s) | C | 180 | 15.9 | Coadd 1676 | 2026-06-03 06:04:10 | MASTER-OAGH | (15h 33m 46.25s , +40d 02m 43.1s) | P- | 120 | 17.4 | 1689 | 2026-06-03 06:04:54 | MASTER-OAFA | (15h 32m 34.09s , +40d 16m 14.9s) | C | 60 | 15.8 | 1755 | 2026-06-03 06:05:59 | MASTER-OAFA | (15h 32m 33.86s , +40d 16m 15.8s) | C | 60 | 15.5 | 1804 | 2026-06-03 06:06:18 | MASTER-OAGH | (15h 33m 41.29s , +40d 02m 06.6s) | P- | 120 | 17.4 | 1824 | 2026-06-03 06:07:08 | MASTER-OAFA | (15h 32m 33.78s , +40d 16m 13.7s) | C | 60 | 15.6 | 1884 | 2026-06-03 06:07:08 | MASTER-OAFA | (15h 32m 33.73s , +40d 16m 14.9s) | C | 180 | 15.9 | Coadd 1890 | 2026-06-03 06:08:14 | MASTER-OAFA | (15h 32m 33.62s , +40d 16m 13.5s) | C | 60 | 15.5 | 1955 | 2026-06-03 06:09:20 | MASTER-OAFA | (15h 32m 33.33s , +40d 16m 14.8s) | C | 60 | 15.1 | 2087 | 2026-06-03 06:11:32 | MASTER-OAFA | (15h 32m 32.85s , +40d 16m 17.2s) | C | 60 | 14.9 | 2285 | 2026-06-03 06:14:49 | MASTER-OAFA | (15h 32m 32.35s , +40d 16m 15.8s) | C | 60 | 12.8 | 2416 | 2026-06-03 06:17:01 | MASTER-OAFA | (15h 32m 31.97s , +40d 16m 14.5s) | C | 60 | 12.7 | 2482 | 2026-06-03 06:18:07 | MASTER-OAFA | (15h 32m 31.82s , +40d 16m 13.7s) | C | 60 | 12.8 | 2542 | 2026-06-03 06:18:07 | MASTER-OAFA | (15h 32m 31.54s , +40d 16m 17.3s) | C | 180 | 15.8 | Coadd 2548 | 2026-06-03 06:19:12 | MASTER-OAFA | (15h 32m 31.62s , +40d 16m 12.7s) | C | 60 | 15.1 | 2614 | 2026-06-03 06:20:18 | MASTER-OAFA | (15h 32m 31.86s , +40d 16m 06.4s) | C | 60 | 16.0 | 2679 | 2026-06-03 06:21:23 | MASTER-OAFA | (15h 32m 31.35s , +40d 16m 10.4s) | C | 60 | 15.9 | 2744 | 2026-06-03 06:22:29 | MASTER-OAFA | (15h 32m 30.72s , +40d 16m 16.0s) | C | 60 | 16.4 | 2810 | 2026-06-03 06:23:35 | MASTER-OAFA | (15h 32m 30.85s , +40d 16m 11.4s) | C | 60 | 16.3 | 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/44788. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...