TITLE: GCN CIRCULAR NUMBER: 33904 SUBJECT: LIGO/Virgo S230601bf: Global MASTER-Net observations report DATE: 23/06/02 13:46:39 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-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) started inspect of the LIGO/Virgo S230601bf errorbox 86 sec after trigger time at 2023-06-01 22:43:00 UT, with upper limit up to 19.5 mag. The observations began at zenith distance = 45 deg. The sun altitude is -80.0 deg. MASTER-OAFA robotic telescope located in Argentina (OAFA observatory of San Juan National University) started inspect of the LIGO/Virgo S230601bf errorbox 543 sec after trigger time at 2023-06-01 22:50:37 UT, with upper limit up to 16.9 mag. Observations started at twilight. The observations began at zenith distance = 73 deg. The sun altitude is -14.9 deg. The galactic latitude b = 19 deg., longitude l = 197 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/ligo_1.php?id=11922 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 92 | 2023-06-01 22:43:00 | MASTER-SAAO | (20h 25m 56.59s , -39d 52m 05.8s) | C | 10 | 17.2 | 117 | 2023-06-01 22:43:00 | MASTER-SAAO | (20h 25m 56.59s , -39d 52m 05.8s) | C | 60 | 18.4 | Coadd 92 | 2023-06-01 22:43:00 | MASTER-SAAO | (20h 24m 51.97s , -39d 51m 33.9s) | C | 10 | 17.3 | 117 | 2023-06-01 22:43:00 | MASTER-SAAO | (20h 24m 51.97s , -39d 51m 33.9s) | C | 60 | 18.4 | Coadd 126 | 2023-06-01 22:43:29 | MASTER-SAAO | (20h 26m 02.38s , -39d 51m 46.0s) | C | 20 | 17.7 | 126 | 2023-06-01 22:43:29 | MASTER-SAAO | (20h 24m 57.73s , -39d 51m 14.1s) | C | 20 | 17.7 | 182 | 2023-06-01 22:44:20 | MASTER-SAAO | (20h 25m 59.84s , -39d 50m 18.5s) | C | 30 | 17.9 | 182 | 2023-06-01 22:44:20 | MASTER-SAAO | (20h 24m 55.25s , -39d 49m 46.7s) | C | 30 | 18.0 | 236 | 2023-06-01 22:45:10 | MASTER-SAAO | (20h 25m 59.76s , -39d 51m 50.8s) | C | 40 | 18.1 | 296 | 2023-06-01 22:45:10 | MASTER-SAAO | (20h 25m 59.76s , -39d 51m 50.8s) | C | 160 | 19.0 | Coadd 236 | 2023-06-01 22:45:10 | MASTER-SAAO | (20h 24m 55.12s , -39d 51m 18.1s) | C | 40 | 18.2 | 296 | 2023-06-01 22:45:10 | MASTER-SAAO | (20h 24m 55.12s , -39d 51m 18.2s) | C | 160 | 19.1 | Coadd 301 | 2023-06-01 22:46:09 | MASTER-SAAO | (20h 26m 02.28s , -39d 50m 14.3s) | C | 50 | 18.1 | 301 | 2023-06-01 22:46:09 | MASTER-SAAO | (20h 24m 57.64s , -39d 49m 42.0s) | C | 50 | 18.3 | 392 | 2023-06-01 22:47:30 | MASTER-SAAO | (20h 25m 57.11s , -39d 51m 06.3s) | C | 70 | 18.4 | 392 | 2023-06-01 22:47:30 | MASTER-SAAO | (20h 24m 52.44s , -39d 50m 32.7s) | C | 70 | 18.5 | 503 | 2023-06-01 22:49:11 | MASTER-SAAO | (20h 24m 51.59s , -39d 49m 33.4s) | C | 90 | 18.7 | 503 | 2023-06-01 22:49:11 | MASTER-SAAO | (20h 25m 56.26s , -39d 50m 07.1s) | C | 90 | 18.6 | 628 | 2023-06-01 22:49:11 | MASTER-SAAO | (20h 24m 51.59s , -39d 49m 33.3s) | C | 340 | 19.4 | Coadd 628 | 2023-06-01 22:49:11 | MASTER-SAAO | (20h 25m 56.26s , -39d 50m 07.0s) | C | 340 | 19.5 | Coadd 598 | 2023-06-01 22:50:37 | MASTER-OAFA | (07h 28m 41.32s , +23d 12m 59.6s) | C | 110 | 16.2 | 748 | 2023-06-01 22:50:37 | MASTER-OAFA | (07h 28m 41.33s , +23d 12m 59.5s) | C | 410 | 16.9 | Coadd 623 | 2023-06-01 22:51:01 | MASTER-SAAO | (20h 26m 02.23s , -39d 51m 08.2s) | C | 110 | 18.6 | 623 | 2023-06-01 22:51:01 | MASTER-SAAO | (20h 24m 57.50s , -39d 50m 33.1s) | C | 110 | 18.7 | 750 | 2023-06-01 22:52:58 | MASTER-OAFA | (07h 28m 46.73s , +23d 13m 32.6s) | C | 130 | 16.1 | 779 | 2023-06-01 22:53:23 | MASTER-SAAO | (20h 25m 55.86s , -39d 52m 09.6s) | C | 140 | 18.7 | 779 | 2023-06-01 22:53:23 | MASTER-SAAO | (20h 24m 51.07s , -39d 51m 33.1s) | C | 140 | 18.8 | 931 | 2023-06-01 22:55:39 | MASTER-OAFA | (07h 28m 44.45s , +23d 14m 48.4s) | C | 170 | 16.6 | 1138 | 2023-06-01 22:59:01 | MASTER-OAFA | (07h 28m 44.40s , +23d 13m 39.6s) | C | 180 | 16.5 | 2232 | 2023-06-01 23:17:15 | MASTER-OAFA | (07h 28m 43.73s , +23d 14m 28.1s) | C | 180 | 15.8 | 2443 | 2023-06-01 23:20:46 | MASTER-OAFA | (07h 28m 43.70s , +23d 13m 13.2s) | C | 180 | 16.0 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited.