Most important properties for the two fitted functions: Gaussian as open circles (only two upper panels, partially superposed) and Bi-Gaussian as filled circles, as a function of orbital phase (with an arbitrary zero-point) for the case of an equatorial spot with a a filling factor of 1% on an edge-on star with v sini of 7 km s^-1. Upper left: center of the two fitted functions as a function of orbital phase; Upper right: FWHM of the two functions; on the two lower panels, we have the asymmetry A (bottom left) and the ΔV indicator (bottom right) for the Bi-Gaussian fitting.