Wiggle in the jet axis of DO Tau: black dots with associated error bars show the jet axis displacement, measured with respect to the blue-shifted jet PA. On the red-shifted jet side (left), grey dots show measurements before correction for a possible misalignment of 1° of the red-shifted jet. Top panel: the red solid curve shows the orbital solution fitted to the blue-shifted jet axis wiggling. Bottom panel: the solid cyan curve shows the precession solution fitted to the blue-shifted jet axis wiggling. The dashed cyan curve shows the same precession solution computed for the red-shifted jet, but adjusted for a phase shift and an increased precession angle (by a factor 2.5). See text for more details.