Power density spectrum in log-scale axes. The peak around 4 μHz is probably the signature of the stellar rotation; the peak at 23.2 μHz is an artifact due to the low-Earth orbit. The black curve corresponds to a box-car-averaged spectrum, with a varying smoothing window (the size of the window increases linearly with frequency). The dashed line represents the white-noise component; the background is modeled with two Harvey-like components indicated by the dotted lines.