Examples of the frequency shift maps for different distant views of the oscillating slender torus. The colour boxes on the right display the false colours scale of frequency shift values. The left column corresponds to the case of the ER axisymmetric dual mode. The right column corresponds to the case of the RP-like non-axisymmetric dual mode. The rows of the figure correspond to spin values a = 0, a = 0.5 and a = 0.96, respectively.