Directions of the orbital angular momenta of particles of the infalling galaxy for merger model 7.5deg100vel (left) and fly-by model 5deg200vel (right) at the final snapshot after 10 Gyr of calculation. Particles which have prograde motions have 0° < φ < 180°, those with retrograde motions have 180° < φ < 360°. In both cases two distinct and significant populations, one pro- and one retrograde, show up. θ = 0° points towards the target galaxy spin direction (“north”). Merger: the 20 000 plotted particles were randomly chosen from all 10⁵ particles with radial distances 0   kpc ≤ r ≤ 170   kpc from the centre of the merged galaxies. They show a wide distribution, characteristic for the more chaotic motions after the merger. It can be seen that the bulk of pro- and retrograde particles have precessed away from the expected positions at θ = 90°, φ = 90° or φ = 270° respectively, but still lie within the 60–degree circles-of-acceptance (COA) for mergers. Fly-by: the plot includes all particles which have radial distances of less than 400 kpc from the target galaxy. Both the particles with prograde and the ones with retrograde motion remain close to the expected orbital angular momenta. They lie well within the 30-degree COAs for fly-bys. Compare to Fig. 12 which plots the MW satellite galaxy distribution in a similar coordinate system.