QUALITY ASSESSMENT OF SATELLITE LASER RANGING STATIONS OPERATING IN 2020

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The paper assesses the quality of satellite laser ranging stations that were operational in 2020. The assessment is based on the results obtained from the LAGEOS-1 and LAGEOS-2 satellites between 2011 and 2020. In 2020, 41 SLR stations conducted laser observations on both LAGEOS satellites. Out of these stations, 20 had been making observations for ten years, while some stations started their observations during this period, resulting in a shorter observation period. NASA's GEODYN-II orbital software was used to compute the satellite orbits for fifteen core stations. The accuracy of the observations from each station was evaluated by determining the stability of the designated coordinates (3DRMS) in the International Terrestrial Reference Frame 2020. The results show that 16 stations achieved accuracy ranging from 4 mm to 10 mm, 17 stations between 10 mm and 15 mm, and 8 stations above 15 mm. Similarly, the standard deviation of the determined coordinates ranged from 1.0 mm to 2.6 mm, from 3.0 mm to 4.0 mm, and above 4.0 mm, respectively. The discussion focuses on the reasons for the inadequate accuracy in determining the coordinates for most stations. These reasons include a lack of sufficient normal points for most stations, a significant random scatter of normal points in the orbit, and insufficient long-term stability of systematic deviations. It is important to note that the results for both LAGEOS satellites are highly consistent.