Potential errors of the SH and double EH models. (A). Potential of 67P assumed to be a homogeneous polyhedron of density 530 kg m⁻³ on the reference sphere. (B). Evaluation errors of SH up to degree 5. (C). Evaluation errors up to degree 15. (D). Polyhedral potential of 67P over the reference ellipsoids. The area inside the polyhedral shape is excluded. (E). Evaluation errors of double EH up to degree 5. (F). Evaluation errors of double EH up to degree 15.