White light curve of Qatar-1b. From top to bottom, the left panel of the figure shows the raw light curve in red. The air-mass model is overplotted in dashed lines. Artificially shifted below, the white light curve after subtracting the air-mass model is indicated in blue and the best-fit transit model is shown in a black continuous line. Finally, the residuals are shown in green. Error bars in all figures were enlarged to meet the standard deviation of the residuals. The right panel of the figure shows the raw white light curve in red points, along with the best-fit transit and detrending models in black dashed line for f₅(t). The pink light curve corresponds to the raw data when the best-fit air-mass component has been subtracted, along with the sinusoidal time-dependent variability overplotted in a black thin continuous line. Blue points correspond to a fully detrended transit light curve; the best-fit transit model is overplotted in a black thick line. Below in green, the residual light curve obtained subtracting the best-fit transit model to the blue points (equivalently, subtracting the dashed line to the red points) can be seen. Everything has been artificially shifted.