Kinematic and spatial location of the observed stars. Left panel: vector point diagram of the 30 observed stars showing the α and δ components of the measured HST PMs referred to the systemic value (μ_α cos δ = −4.979 mas yr⁻¹, μ_δ = −7.431 mas yr⁻¹) quoted by Vasiliev & Baumgardt (2021). The large dashed circle is centered on (0, 0) and has a radius equal to 3 × σ_PM, with σ_PM = 0.5 mas yr⁻¹ being the measured dispersion of the PM distribution for the Terzan 6 bright stars. The three stars beyond this circle (marked with a cross) are considered as field interlopers. Right panel: distribution of the observed stars in the plane of the sky with respect to the cluster center (same symbols as in the left panel). A consistent fraction of them lie within the dashed circle marking the cluster half-light radius of 26.4″, while the remaining stars lie well within the tidal radius (see, e.g., Harris 1996).