TITLE: GCN CIRCULAR NUMBER: 34477 SUBJECT: Swift GRB230818.98: Global MASTER-Net observations report DATE: 23/08/18 23:36:25 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V. Lipunov, V.Kornilov, E.Gorbovskoy, K.Zhirkov, N.Tyurina, P.Balanutsa, A.Kuznetsov, D. Vlasenko, G.Antipov, D.Zimnukhov, V.Senik, E.Minkina, A.Chasovnikov, V.Topolev, D.Kuvshinov, D.Cheryasov, Ya.Kechin (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 (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), A. Gabovich, V.Yurkov (Blagoveschensk Educational State University) MASTER-Tavrida robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Russia (Lomonosov MSU, SAI Crimea astronomical station) was pointed to the Swift GRB230818.98 (trigger No 1186032,19h 03m 31.90s , +40d 52m 34.7s, R=0.05) errorbox 19 sec after notice time and 37 sec after trigger time at 2023-08-18 23:28:11 UT, with upper limit up to 18.6 mag. The observations began at zenith distance = 48 deg. The sun altitude is -28.4 deg. MASTER-Kislovodsk robotic telescope located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) was pointed to the Swift GRB230818.98 errorbox 24 sec after notice time and 41 sec after trigger time at 2023-08-18 23:28:15 UT, with upper limit up to 17.9 mag. The observations began at zenith distance = 54 deg. The sun altitude is -26.2 deg. The galactic latitude b = 15 deg., longitude l = 72 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2256038 We obtain a following upper limits. Tmid-T0 | Site |Filt.| Expt. | Limit| Comment _________|_____________________|_____|_______|______|________ 42 | MASTER-Tavrida | C | 10 | 17.3 | 47 | MASTER-Kislovodsk | P- | 10 | 14.2 | 47 | MASTER-Kislovodsk | P| | 10 | 16.4 | 57 | MASTER-Kislovodsk | P| | 30 | 17.1 | Coadd 59 | MASTER-Tavrida | C | 10 | 17.9 | 65 | MASTER-Kislovodsk | P- | 10 | 14.2 | 65 | MASTER-Kislovodsk | P| | 10 | 16.5 | 76 | MASTER-Tavrida | C | 10 | 18.0 | 83 | MASTER-Kislovodsk | P- | 10 | 14.5 | 83 | MASTER-Kislovodsk | P| | 10 | 16.5 | 99 | MASTER-Tavrida | C | 20 | 18.3 | 105 | MASTER-Kislovodsk | P- | 20 | 16.0 | 105 | MASTER-Kislovodsk | P| | 20 | 17.2 | 130 | MASTER-Kislovodsk | P| | 70 | 17.8 | Coadd 126 | MASTER-Tavrida | C | 20 | 18.3 | 134 | MASTER-Kislovodsk | P- | 20 | 16.0 | 134 | MASTER-Kislovodsk | P| | 20 | 17.0 | 159 | MASTER-Tavrida | C | 30 | 18.4 | 167 | MASTER-Kislovodsk | P- | 30 | 16.1 | 167 | MASTER-Kislovodsk | P| | 30 | 17.5 | 201 | MASTER-Tavrida | C | 40 | 18.6 | 210 | MASTER-Kislovodsk | P- | 40 | 16.1 | 210 | MASTER-Kislovodsk | P| | 40 | 17.7 | 253 | MASTER-Tavrida | C | 50 | 18.6 | 263 | MASTER-Kislovodsk | P- | 50 | 16.2 | 263 | MASTER-Kislovodsk | P| | 50 | 17.8 | 326 | MASTER-Kislovodsk | P- | 60 | 16.2 | 326 | MASTER-Kislovodsk | P| | 60 | 17.9 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited.