Fourier power spectrum (top-left) and spectral window (bottom-left) for the TIGRE solar S-index time series for frequencies between 0 and 2 d⁻¹. The green dashed line in the power spectrum yields ν_Car, while the red, cyan and blue dashed lines in the spectral window plot identify the main aliasing frequencies which are respectively 0.0339 d⁻¹, 0.9661 d⁻¹, and 1.0000 d⁻¹. Right: Same details, but zooming on the frequency range between 0 and 0.1 d⁻¹. The dashed black line corresponds to 2ν_Car.