Rms of the shift along the x-axis of a rotating reference frame as a function of its rotational angle (see text). In red, we show the case of solar activity. In blue, we show the case of five times the solar activity. In all cases, we consider that the instrumental noise is 0 (plain lines) or 0.35 microas (dashed lines). The vertical dashed line shows the angle of the inclination of the planet orbital plane.