ξ(Δr_⊥, Δv) measured for a realistic mock data set with no correlation. (a) In the scatter plot the blue (gray) dots correspond to the mock data (random) pairs, and the side panels show the respective projections in number counts. In the 2d-histogram the color scale indicates ξ(Δr_⊥, Δv) between -1 and 1. (b) Velocity projection of ξ(Δr_⊥, Δv). The shaded pink regions indicate 1σ errors.