TITLE: GCN CIRCULAR NUMBER: 30959 SUBJECT: IceCube Alert 211023.36: Global MASTER-Net observations report DATE: 21/10/23 17:52:18 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru> V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, P.Balanutsa, A.Kuznetsov, F.Balakin, V.Vladimirov, D. Vlasenko, I.Gorbunov, D.Zimnukhov, V.Senik, T.Pogrosheva, D.Kuvshinov, D. Cheryasov (Lomonosov Moscow State University, SAI, Physics Department), R. Podesta, C.Lopez, F. Podesta, C.Francile (Observatorio Astronomico Felix Aguilar OAFA), R. Rebolo, M. Serra (The Instituto de Astrofisica de Canarias), D. Buckley (South African Astronomical Observatory), O.A. Gres, N.M. Budnev, O.Ershova (Irkutsk State University, API), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), V. Yurkov, A. Gabovich, Yu. Sergienko (Blagoveschensk Educational State University) 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 211023.36 (trigger No 55176071,16h 54m 20.18s , -01d 50m 11.0s, R=0.584) errorbox 33119 sec after notice time and 33168 sec after trigger time at 2021-10-23 17:44:07 UT, with upper limit up to 15.1 mag. Observations started at twilight. The observations began at zenith distance = 68 deg. The sun altitude is -10.5 deg. The galactic latitude b = 24 deg., longitude l = 17 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1762298 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 33199 | 2021-10-23 17:44:07 | MASTER-SAAO | (16h 54m 34.56s , -00d 38m 15.7s) | C | 60 | 13.8 | 33279 | 2021-10-23 17:45:26 | MASTER-SAAO | (17h 02m 36.87s , -00d 38m 33.1s) | C | 60 | 15.1 | 33358 | 2021-10-23 17:46:46 | MASTER-SAAO | (16h 55m 32.02s , -02d 31m 53.9s) | C | 60 | 14.4 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited.