Cartography of the Surface Markings of Mercury

From 98 photographic plates showing surface markings of the planet Mercury, taken at Pic-du-Midi and New Mexico State Observatories and grouped at the Meudon IAU Planetary Data Center, 40 were measured to derive an improved map of the surface features of Mercury. High resolution visual drawings available from Pic-du-Midi and Meudon Observatories were used to refine some details, and coordinates are given for selected features. The rotation axis is found to be perpendicular to the plane of the orbit within 3°, and the rotation period derived is 58.644 ± 0.009 days, not significantly different from the two-thirds revolution period.