Multiplied Scargle periodograms (top panels) of all three individual FIES, HERMES, and SONG datasets, after rescaling each one of them to their dominant frequency (see text), compared with the periodogram of the merged dataset (bottom panels) for the first moment of the Si III λ4552 (left) and H_α (right) lines.Thick dashed lines indicate some of the dominant frequencies identified in any of the four periodograms. Thin dotted lines show their ±1 day aliases.