Geometry of the flybys from BepiColombo and Mariner 10 in the MSO coordinate system with average BS and MP models displayed with dashed gray lines. The origin of the MSO coordinate system is at the planetary center of mass, +X is sunward, +Y lies in the orbital plane, perpendicular to +X and opposite to the direction of planetary orbital motion (i.e., +Y is positive toward dusk), and +Z is normal to the orbital plane and positive northward. From left to right: MFB1 (October 1, 2021), MFB2 (June 23, 2022), MFB3 (June 19, 2023), and M10 FB1 (March 29, 1974). Top: trajectories in the XY plane. Bottom: trajectories in the XZ plane. Distances to the planet are given in Mercury radii, 1 R_M = 2440 km. The marks are the time in UTC (HH:MM).