Azimuthal dependence of the effect of Keplerian shear, expressed as the maximum gradient of the Keplerian projected line-of-sight velocity in any direction (left y-axis), or evaluated as the same gradient by the beam size of our ARKS HD 121617 observations (right y-axis). The solid blue versus dashed orange lines show the dependence of the curve on whether orbital or sky azimuths are considered; the former should typically be considered for data that have been de-projected to the orbital plane.