Research on Enhancing the dUT1 Independent Monitoring Capability of China Next-Generation VLBI Network

The Earth orientation parameters play a crucial role in positioning and navigation. Very-long-baseline interferometry (VLBI) stands as the sole technology that offers a comprehensive set of Earth orientation parameters. The technology offers a highly precise measurement of dUT1. In order to facilitate diverse space activities, it is imperative for China to establish an independent capability for high-precision dUT1 support. To this end, China Next-Generation VLBI Network (CNVN) has been constructed. In this paper, VieSched++ is employed to identify the optimal single baseline for dUT1 estimation among 11 potential VLBI Global Observing System antenna locations in China, followed by the determination of an optimized 3-station network. We integrated CNVN with a space-tracking vessel to enhance the precision of dUT1 estimation. The results demonstrate that the optimal single baseline between Jiamusi and Kashi in China yields dUT1 estimates with a mean formal error of less than 13 μs and a repeatability better than 33 μs during observations lasting for both 1 and 1.5 h. The optimal 3-station network comprising Jiamusi, Kashi, and Shanghai demonstrates the capability to provide dUT1 estimates with an mean formal error of less than 8 μs and a repeatability of less than 31 μs. The North Atlantic Ocean is identified as the optimal location for the space-tracking vessel when combined with the 4-antenna CNVN, enabling an estimation of dUT1 with an mean formal error of less than 5 μs and a repeatability of less than 15 μs after 1 h of observation.