Exploring the effect of different VLBI Networks on EOPs estimation.

One of the key determinants influencing the accuracy and reliability of Earth Orientation Parameters (EOP) is the network Very Long Baseline Interferometry (VLBI) geometry. VLBI is a high-precision radio astronomy technique that involves multiple radio telescopes spread across the globe, working together as a network. The geometric configuration of these telescopes plays a crucial role in the quality of the data collected and, consequently, the accuracy of EOP measurements. The distribution and arrangement of the VLBI network antennas impact the triangulation process used to determine the positions of celestial radio sources, contributing to the calculation of Earth's rotation parameters. An optimal VLBI geometry ensures a well-constrained and robust observational setup, leading to more precise EOP results crucial for many scientific applications. In this study, we analyze the impact of using different VLBI networks on the EOP estimation. Due to its nature the Continuous VLBI Campaigns (CONT) give a good basis to investigate these effects. For this purpose, we artificially create different networks with distinct configurations (e.g. removing VLBI antennas located in the northern hemisphere and vice versa, taking out the longest north-south baselines or the east-west baselines). This sensitivity analysis will contribute to the refinement of the EOP and will help to fulfill the stringent GGOS targets (i.e. a frame with accuracy at epoch of 1 mm or better and a stability of 0.1 mm/y). Acknowledgment. This research was supported partially by Spanish Projects PID2020-119383GB-I00 funded by Ministerio de Ciencia e Innovacin (MCIN/AEI/10.13039/501100011033); PROMETEO/2021/030 and SEJIGENT/2021/001, funded by Generalitat Valenciana; and the European UnionNextGenerationEU (ZAMBRANO 21-04).