Fourier transforms of different period sets. From top to bottom: FT of the periods of Table 4 (black solid line), test FTs of 5 of the 20 “aliased” period lists (coloured lines), FT of the combined list (black dashed line) using the periods determined by Handler et al. (2003) and five additional periods from the Konkoly2007 dataset (altogether 14 items). The vertical dotted line denotes the 31.4 s spacing value.