Cuts through panels b) and c) of Fig. 1 along the ridges for n = 0 through 4. Dotted black line shows the results for the noise evaluated half way between the n = 1 and n = 2 ridges. For the phase convention see the caption to Fig. 1. Note that the large oscillations in the phase just below 2 mHz are caused by the very low amplitude in that region and thus large noise sensitivity. This, in turn, also results in problems trying to unwrap the phase, which might otherwise have improved the presentation.