TITLE: GCN CIRCULAR NUMBER: 40256 SUBJECT: IceCube Alert 250426.74: Global MASTER-Net observations report DATE: 25/04/27 00:27:01 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-SAAO robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in South Africa (South African Astronomical Observatory) was pointed to the IceCube Alert 250426.74 (trigger No 52432631,19h 45m 04.08s , +20d 41m 27.6s, R=0.56) errorbox 23060 sec after notice time and 23122 sec after trigger time at 2025-04-27 00:10:20 UT, with upper limit up to 17.5 mag. The observations began at zenith distance = 76 deg. The sun altitude is -61.8 deg.
The galactic latitude b = -2 deg., longitude l = 58 deg.
Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2853923
We obtain a following upper limits.
Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________
23152 | 2025-04-27 00:10:20 | MASTER-SAAO | (19h 42m 54.59s , +20d 09m 14.4s) | C | 60 | 17.5 | Filter C is a clear (unfiltred) band.
The observation and reduction will continue. The message may be cited.
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