Comparison of one- and two-term Fourier analysis for identifying the rotation period. Top: phased TESS LC for an example mCP star with a decidedly double-waved pattern at the rotational period (i.e. two maxima and two minima per rotation). Middle: standard single-term frequency analysis, showing that the strongest peak is at 2×f_rot. Bottom: two-term frequency analysis, where the strongest peak is at f_rot.