Azimuthal profile of the Q_φ(φ) images averaged over an annulus of 35–70 au. The colored dots are calculated from the observations, with the uncertainties being the standard deviation over all selected cycles. The overplotted curves are calculated from the convolved fitted model. The vertical dashed lines indicate the position angles of the minor axis, smin(W) and smin(E), in the west and east directions, and the major axis, smaj(N) and smaj(S), in the north and south directions.