Orbits of Helios and the candidate comets. The purple diamond marks the dust detections at η ≈ 135°. The lines attached to the diamond indicate the approximate impact directions (speed vector) of trail particles from these comets in the spacecraft-centric reference frame as derived from the IMEX model. The X-Y plane is the ecliptic plane with vernal equinox oriented towards the +X direction. Comet orbits are shown for the period 1975–1980, with locations of ascending nodes (asterisks) and descending nodes (plus signs) superimposed.