The dependence of the previous perihelion distance on the reciprocal of the previous semimajor axis for C/2001 Q4 (DIST2 variant with the standard NG model). Each dot in the central part of figure represents an individual cometary orbit from the swarm of 5000 VC orbits propagated to the previous perihelion (~3 million years back in time). Results of two different calculations are shown: without stellar perturbations (the central upper plot) and with stellar perturbation included (the lower one). The centres of the big circles define the positions of the respective nominal orbits. For the variant without stellar perturbations, boundary distributions of 1/a_prev and q_prev are also plotted.