TITLE: GCN CIRCULAR NUMBER: 35313 SUBJECT: Swift GRB231210.90: Global MASTER-Net OT detection DATE: 23/12/10 21:42:31 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs D. Buckley (South African Astronomical Observatory), 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), 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-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 GRB231210.90 92 sec after notice time and 124 sec after trigger time at 2023-12-10 21:31:08 UT. On our first (10s exposure) set we found 1 optical transient within Swift error-box (ra=95.7708 dec=-48.3583 r=0.05) brighter than 16.9. T-Tmid Date Time Expt. Ra Dec Mag ---------|---------------------|-------|-----------------|-----------------|------- 129 2023-12-10 21:31:08 10 (06h 23m 11.01s , -48d 22m 20.5s) 16.3 The 5-sigma upper limit has been about 16.9mag The message may be cited.