paper: Lunar Simulation at Le Manio

Our survey at Le Manio revealed a coherent arc of radial stones, at least five of which were equally long, equally separated and set to a radius of curvature that suggested a common centre. It appears the astronomers at Le Manio understood that, following three lunar sidereal orbits (after 82 days) the moon would appear again at the same point on the ecliptic at the same time of day