MATHEMATICS, cilt.8, sa.6, ss.1-15, 2020 (SCI-Expanded)
Very Long Baseline Interferometry (VLBI) plays an indispensable role in the realization of
global terrestrial and celestial reference frames and in the determination of the full set of the Earth
Orientation Parameters (EOP). The main goal of this research is to assess the quality of the VLBI
observations based on the sensitivity and robustness criteria. Sensitivity is defined as the minimum
displacement value that can be detected in coordinate unknowns. Robustness describes the
deformation strength induced by the maximum undetectable errors with the internal reliability
analysis. The location of a VLBI station and the total weights of the observations at the station are
most important for the sensitivity analysis. Furthermore, the total observation number of a radio
source and the quality of the observations are important for the sensitivity levels of the radio
sources. According to the robustness analysis of station coordinates, the worst robustness values are
caused by atmospheric delay effects with high temporal and spatial variability. During CONT14, it
is determined that FORTLEZA, WESTFORD, and TSUKUB32 have robustness values changing
between 0.8 and 1.3 mm, which are significantly worse in comparison to the other stations. The radio
sources 0506-612, NRAO150, and 3C345 have worse sensitivity levels compared to other radio
sources. It can be concluded that the sensitivity and robustness analysis are reliable measures to
obtain high accuracy VLBI solutions.