PSD of the VIRGO/SPMs light curve (from 23.01.1996 to 23.11.2023). Higher frequencies are displayed between 3270 and 3750 μHz, showing the large frequency separation (δν) noted between modes ℓ = 0 and ℓ = 1 for n = 23. Modes are marked by vertical lines with different colours: n = 22 in light blue, n = 23 in orange, n = 24 in yellow, n = 25 in cyan, and n = 26 in dark blue). ℓ = 0 are in continuous, ℓ = 1 in dashed, ℓ = 2 in dotted, and ℓ = 3 in dot-dashed lines. In the subplot: Window of Δω = 8 μHz used to reconstruct modes energy time series is shown around modes (n = 25, ℓ = 0) in light brown and (n = 24, ℓ = 2) in dark brown.