TITLE: GCN CIRCULAR NUMBER: 35601 SUBJECT: Swift GRB240123.46: Global MASTER-Net observations report DATE: 24/01/23 11:26:57 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V. Lipunov, V.Kornilov, E. Gorbovskoy, K. Zhirkov, N.Tyurina, P.Balanutsa, A.Kuznetsov, V.Senik, D. Vlasenko, G.Antipov, D.Zimnukhov, E.Minkina, A.Chasovnikov, V.Topolev, D.Kuvshinov, D. Cheryasov, Ya.Kechin, Yu.Tselik, A. Sosnovskij (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. Gress, N.M. Budnev, O.Ershova (Irkutsk State University, API), L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), V. Yurkov, A. Gabovich (Blagoveschensk Educational State University) MASTER-Tunka robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Russia (Applied Physics Institute, Irkutsk State University) was pointed to the Swift GRB240123.46 (trigger No 1210276,13h 17m 16.56s , +60d 37m 55.2s, R=0.05) errorbox 41 sec after notice time and 121 sec after trigger time at 2024-01-23 11:07:48 UT, with upper limit up to 17.6 mag. Observations started at twilight. The observations began at zenith distance = 68 deg. The sun altitude is -13.5 deg. The galactic latitude b = 56 deg., longitude l = 117 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2363206 We obtain a following upper limits. Tmid-T0 | Site |Filt.| Expt. | Limit| Comment _________|_____________________|_____|_______|______|________ 131 | MASTER-Tunka | C | 20 | 17.6 | 160 | MASTER-Tunka | C | 20 | 17.6 | 186 | MASTER-Tunka | C | 15 | 17.5 | 209 | MASTER-Tunka | C | 15 | 17.5 | 229 | MASTER-Tunka | C | 10 | 17.4 | 247 | MASTER-Tunka | C | 10 | 17.3 | 265 | MASTER-Tunka | C | 10 | 17.4 | 284 | MASTER-Tunka | C | 10 | 17.1 | 302 | MASTER-Tunka | C | 10 | 17.4 | 320 | MASTER-Tunka | C | 10 | 17.5 | 339 | MASTER-Tunka | C | 10 | 17.4 | 357 | MASTER-Tunka | C | 10 | 17.3 | 375 | MASTER-Tunka | C | 10 | 17.5 | 394 | MASTER-Tunka | C | 10 | 17.4 | 412 | MASTER-Tunka | C | 10 | 17.2 | 430 | MASTER-Tunka | C | 10 | 17.4 | 448 | MASTER-Tunka | C | 10 | 17.3 | 466 | MASTER-Tunka | C | 10 | 17.4 | 486 | MASTER-Tunka | C | 10 | 17.4 | 504 | MASTER-Tunka | C | 10 | 17.4 | 522 | MASTER-Tunka | C | 10 | 17.4 | 541 | MASTER-Tunka | C | 10 | 17.4 | 559 | MASTER-Tunka | C | 10 | 17.4 | 577 | MASTER-Tunka | C | 10 | 17.4 | 595 | MASTER-Tunka | C | 10 | 17.4 | 613 | MASTER-Tunka | C | 10 | 17.4 | 632 | MASTER-Tunka | C | 10 | 17.4 | 651 | MASTER-Tunka | C | 10 | 17.4 | 669 | MASTER-Tunka | C | 10 | 17.4 | 706 | MASTER-Tunka | C | 10 | 17.4 | 724 | MASTER-Tunka | C | 10 | 17.4 | 743 | MASTER-Tunka | C | 10 | 17.4 | 761 | MASTER-Tunka | C | 10 | 17.5 | 781 | MASTER-Tunka | C | 10 | 17.4 | 799 | MASTER-Tunka | C | 10 | 17.5 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited.