Gaia EDR3 foreground cleaning procedure. a. Proper motions of queried sources that satisfy the initial parallax and radial cut (blue) and those that do not (red). The Sculptor dSph proper motion determined by Piatek et al. (2006) is plotted (black plus sign). b. Elliptical distance from the center of the adopted PM profile (green curve in panel a.) as a function of magnitude. Points are color coded according to their π/σ _π , to highlight the distribution of likely foreground sources (which will have large values of π/σ _π ). The blue curve represents the envelope outside of which a source is classified as foreground. c. I vs. (V − I) CMD displaying the removed sources (red dots) and retained sources (blue dots) with a zoomed view of the TRGB shown in the inset. d. Spatial distribution of sources identified as foreground (red dots) and members of Sculptor (blue dots).