Radial velocities of a Lambert sphere of 15 arcsec of diameter, with a retrograde rotation of 1 m s⁻¹ seen with an atmospheric seeing of 0, 1, and 3 arcsec respectively (black, red, blue curves), and phase angles α = [0, 45, 90, 135]°. We assumed that radial velocities are measured on solar reflected lines (Fraunhofer), which explains why radial velocities can be larger than ±1 m s⁻¹. Left panels are slices along the equator and right frames are maps. Top maps are the true radial velocity signal, and bottom are the same degraded by a 3-arcsec atmospheric seeing.