Time evolution of the coefficient for the Zernike polynomial with n = 3 and m = − 1 for v_m. The top left panel visualizes this Zernike polynomial, the top right panel shows the time series of the amplitude of the coefficient, both before (blue curve) and after (red curve) filtering in time. The bottom left panel shows the power spectrum of the unfiltered time series. The dashed vertical lines indicate examples of frequencies that are affected by the orbit, by the orbit of the Earth around the Sun (red lines), or by the orbit of SDO around the Earth (black lines). See text for more details about the filtering. The residuals after subtracting the filtered from the unfiltered time series are shown in the bottom right panel.