Sketch illustrating how the orientation of the rotation axis was determined. This is an on-sky projection with a similar orientation to Fig. 1. Circular plane b is perpendicular to vector a, which represents the direction of the shortest axis of inertia of the comet’s nucleus. Line segment c shows the on-sky direction of the axis of the corkscrew pattern. Angular momentum vector d indicates our solution, which should be located at plane b, and its on-sky projection should coincide with line segment c.