DIM variances A_F(k) (solid) and Ā_F(k) (dashed lines) derived from FORS2 astrometry at any seeing for each k (and k modes mixed); the variances τA_c(k) derived from the model Eq. (24) at τ = 1.019 are shown by circles. Average of A_F(k) and Ā_F(k) for a good 0.4–0.6″ and worse 0.8–1.0″ seeing are shown by dash-dotted and dotted lines, respectively. The right axis τ is the ratio of DIM variances to A₀ = 0.708 mas² estimated with the model Eq. (21).