TITLE: GCN CIRCULAR NUMBER: 33998 SUBJECT: LIGO/Virgo S230618d: Global MASTER-Net observations report DATE: 23/06/18 07:07:11 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-OAFA robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Argentina (OAFA observatory of San Juan National University) started inspect of the LIGO/Virgo S230618d errorbox 65 sec after trigger time at 2023-06-18 02:43:34 UT, with upper limit up to 19.4 mag. The observations began at zenith distance = 65 deg. The sun altitude is -64.0 deg. The galactic latitude b = -75 deg., longitude l = 290 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/ligo_1.php?id=12095 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 156 | 2023-06-18 02:43:34 | MASTER-OAFA | (12h 58m 33.14s , +18d 57m 04.9s) | C | 180 | 19.1 | 367 | 2023-06-18 02:47:06 | MASTER-OAFA | (13h 06m 58.32s , +18d 58m 03.3s) | C | 180 | 19.1 | 803 | 2023-06-18 02:54:21 | MASTER-OAFA | (13h 10m 08.61s , +22d 44m 03.9s) | C | 180 | 19.4 | 1015 | 2023-06-18 02:57:54 | MASTER-OAFA | (13h 07m 40.24s , +20d 49m 58.3s) | C | 180 | 19.1 | 1226 | 2023-06-18 03:01:25 | MASTER-OAFA | (12h 43m 26.12s , +15d 08m 54.7s) | C | 180 | 19.2 | 1698 | 2023-06-18 03:09:16 | MASTER-OAFA | (13h 01m 28.90s , +22d 44m 46.3s) | C | 180 | 19.1 | 1909 | 2023-06-18 03:12:48 | MASTER-OAFA | (12h 51m 41.58s , +15d 07m 53.6s) | C | 180 | 18.8 | 2121 | 2023-06-18 03:16:19 | MASTER-OAFA | (13h 10m 07.81s , +22d 44m 06.4s) | C | 180 | 19.4 | 2332 | 2023-06-18 03:19:50 | MASTER-OAFA | (13h 07m 39.93s , +20d 51m 19.6s) | C | 180 | 18.8 | 2713 | 2023-06-18 03:26:11 | MASTER-OAFA | (13h 16m 15.17s , +20d 51m 36.8s) | C | 180 | 18.7 | 3206 | 2023-06-18 03:34:24 | MASTER-OAFA | (13h 14m 52.07s , +15d 08m 42.1s) | C | 180 | 18.9 | 3417 | 2023-06-18 03:37:56 | MASTER-OAFA | (13h 23m 02.05s , +15d 07m 39.5s) | C | 180 | 18.9 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited.