Initial color and magnitude selection. In gray we plotted the color-magnitude diagram (CMD) of the stars that follow proper motion selection and extinction correction. Red points denote common stars between the selection in gray and the stars observed by the S⁵ survey. Using these stars and a 12 Gyr, [Fe/H] = −1.7 PARSEC isochrone at 13 kpc (dark blue), we define the primary CMD selection as all stars lying in between the orange lines. The selection limit line on the right is positioned there to capture as many main sequence stars as possible while containing most stars in common with the S⁵ survey.