Rubin-GC1 (gold star) in the context of the known Milky Way satellite population, including GCs (black crosses), candidate and confirmed dwarf galaxies (unfilled and filled blue triangles, respectively), and ultrafaint compact satellites discovered in recent surveys; the data are taken from the compilations of A. B. Pace (2025) version 1.1.0 and W. Cerny et al. (2026a). (Left) Absolute magnitude (M_V) versus azimuthally averaged half-light radius (r_1/2). Contours of fixed surface brightness within r_1/2 are shown in gray. (Right) M_V versus heliocentric distance (D_⊙). In both panels, the secondary y-axis displays stellar masses computed assuming a fixed stellar mass-to-light ratio of ϒ = 2M_⊙/L_V.