Normalized integral $I_{\mathrm{c}}^{\ast }(d)$ dependence on distance d to the turbulent phase screen for CSD if the VLT design is with (solid lines) or without a secondary mirror (dashed lines). Integral $⟨I_{\mathrm{F}}^{\ast }(d)⟩$ averaged over all P-stars (different type symbols for each k mode shown) within a sky field No. 12. Integral $I_{\mathrm{F},i}^{\ast }$ for each P-star in those fields (gray symbols, k = 6 only). Integrals were computed for R = 2.1′.