Vector point diagram obtained from Gaia DR3 PMs, for the stars located within 200” from the center of NGC 6553 (gray dots). The 13 spectroscopic targets with measured PM are reported as red filled squares. The dashed circle has a radius equal to 3 × σ_PM, with σ_PM = 0.3 mas yr⁻¹ being the PM dispersion of NGC 6553 member stars. All the spectroscopic targets with measured PM are located within it and have thus been included in this study.