Power spectral density (PSD) on logarithmic scale of a 2 μHz ideal sine wave (black) following the Barycentric Kepler Julian Date (BKJD, see Appendix A for further details). The red curve corresponds to the PSD of the same sine wave multiplied by the Kepler window function. Both PSDs were computed using a Lomb-Scargle algorithm. The blue line is the PSD resulting from converting the timing BKJD of the ideal sine wave (without gaps) into a regular grid and computed using a FFT.