Top: geometry of the line of sight to 3C196 relative to the Sun and comet (not to scale). P represents the point of closest approach of the line of sight to the Sun. Bottom: track of 3C196 relative to the comet (blue dashed line), in the sky plane, overplotted on an image of the comet taken at 20:46 UT on 17 July 2020 by Michael Jäger (reproduced with permission). The green segment of the track marks the period of enhanced scintillation detailed in Sect. 3.