TITLE: GCN CIRCULAR NUMBER: 42910 SUBJECT: IceCube Alert 251130.75: Global MASTER-Net observations report DATE: 25/11/30 23:13:22 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-Tunka robotic telescope [1] located in Russia (Applied Physics Institute, Irkutsk State University) was pointed to the IceCube Alert 251130.75 (trigger No 31953389,15h 18m 58.08s , -05d 39m 25.2s, R=0.95) errorbox 18825 sec after notice time and 18880 sec after trigger time at 2025-11-30 23:08:10 UT, with upper limit up to 15.1 mag. Observations started at twilight. The observations began at zenith distance = 82 deg. The sun altitude is -14.8 deg.

The galactic latitude b = 41 deg., longitude l = 356 deg.

Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3056129

We obtain a following upper limits.

Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________

18910 | 2025-11-30 23:08:10 | MASTER-Tunka | (15h 18m 34.03s , -05d 47m 52.8s) | C | 60 | 14.5 | 18910 | 2025-11-30 23:08:10 | MASTER-Tunka | (15h 18m 53.09s , -05d 55m 00.3s) | C | 60 | 15.1 | 18984 | 2025-11-30 23:09:24 | MASTER-Tunka | (15h 18m 39.40s , -05d 48m 55.2s) | C | 60 | 14.3 | 18984 | 2025-11-30 23:09:24 | MASTER-Tunka | (15h 18m 58.71s , -05d 56m 07.2s) | C | 60 | 15.0 | 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

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