R_D points projected at the sky plane in blue points, with 1σ uncertainties in red. The blue segment is the positive detection from Varages station. Orange and green segments correspond to negative frames acquired in Montsec and Asiago stations, respectively. In black, the dotted line is the best-fitted global limb model described in Sect. 3.1, and the solid line is the model for local topography. The solid gray lines limit the topographic model’s 1σ-error bars. Finally, the filled gray color shows the proposed global limb with topography.