Residual periodogram of the three-planet solution as a function of the blue cut-off wavelength λ_BC. The top periodogram is obtained using the full-spectrum RVs. The bottom periodogram is obtained using the aperture 40 (505.0 nm) as λ_BC. All signals discussed in the text are marked with narrow vertical lines. The horizontal line represents the peak value of peak closer to 320 days. When λ_BC = 433 nm (central periodogram), the emerging 125-day peak is already as high as the activity-induced signal. The 120-day peak is an alias of the most likely period of 200 days for planet candidate d.