Echelle diagram of the amplitude spectra with: dipole frequencies fitted on the power spectra (red circles); l = 0 frequencies from the optimisation (orange diamonds); asymptotic dipole frequencies from the optimisation (white diamonds); and dipole frequencies from fitting the asymptotic model to the fitted frequencies (red diamonds). Left: for a case where 100% of the asymptotic frequencies match the fitted frequencies. Right: for a case where 55% of the asymptotic frequencies match the fitted frequencies.