Mock data for Auriga 23. The blue dots are disc stars that we excluded, i.e. stars with λ_z > 0.8 or stars with λ_z > 0.5 and Z/Z_⊙ > 0.5. The black dots are taken as halo stars and kept in our sample. We divided the data into 7 × 6 bins in r_gc versus θ with the intervals of r_gc = [5, 8, 12, 16, 22, 30, 40, 50] kpc, θ = [0, 10, 20, 30, 40, 55, 90°]; here, we only show three columns to illustrate the data.