LIGO/Virgo S230620z: Global MASTER-Net observations report

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 S230620z errorbox 76 sec after trigger time at 2023-06-20 03:21:05 UT, with upper limit up to 16.8 mag. The observations began at zenith distance = 52 deg. The sun altitude is -71.7 deg. The galactic latitude b = -71 deg., longitude l = 278 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/ligo_1.php?id=12184 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 111 | 2023-06-20 03:21:05 | MASTER-OAFA | (21h 02m 50.10s , -61d 02m 51.3s) | C | 70 | 16.8 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited.