Example of a fit to a transit. Top panel: light curve of five transits, taking as the first transit the reference epoch (BJD = 2455010.79717), with the overplotted blue curve that represents a transit in front of a spotless star, and the model with zero to four spots (red curve). Bottom panel: residuals after subtraction of the spotless model, with the best spot fit (red curve) from zero to four spots. The dashed horizontal lines represent the threshold for spot modelling, which equals ten times the CDPP, and the dotted vertical lines at ±1.18 h limit the fitting portion of the transit, corresponding to ±70° stellar longitudes.