Distributions of the simulated perpendicularity condition in the IBEX-ribbon-center frame. Black circles show the position of the observed IBEX ribbon, shades of red color-coded values of the simulated distribution of (see the colorbar; only are visible due to the definition of the colorscale), and blue circles show the minimum of the simulated distribution. Different panels correspond to different distances from the HP (HP1 definition): (a) 20, (b) 50, and (c) 80 AU for the simulation case B_∞ = 0.3 nT. The LISM inflow (heliospheric nose) direction is marked as Nose, positions of the Voyager 1 and 2 at the time of the HP crossing are denoted as V1 and V2.