Stretching of the pulsation periods in the example of a series of dipole prograde modes. Mode periods were generated using the asymptotic TAR with ν_rot = 20 μHz and P₀ = 4320 s (or 0.05 d). Top panel: before the stretching as they would be seen by an observer. Bottom panel: after the change of reference frame and the stretching, assuming the correct mode identity and rotation rate.