Point mass M31 main progenitor (6.5 × 10¹¹ M_⊙) and the secondary interloper (1.7 × 10¹¹ M_⊙) during the second passage (-5 Gyr to 0 Gyr) of M31 merger model 288 without (smooth line) and with (dashed line) the radially approaching MW point mass (8.14 × 10¹¹ M_⊙). Thick black and brown lines trace the orbit from the n-body simulations that result in the merger. The current Andromeda position is at (0,0,0), and the current MW is on the z-axis. Stars denote the positions at 0 Gyr.