Mean photometric properties in different Voronoi bins: K_S,0 (top), H − K_S (middle), and A_KS ,0 (bottom). The mean K_S,0 indicates that the stars in the central region are slightly fainter than stars in the outer regions, especially in the west. The stars in the centre are slightly redder (higher mean H − K_S ), and in this region, the extinction A_KS is higher. High-velocity stars and foreground stars were excluded. Each bin contains ∼40 stars.