The Macbeath circle, a term coined here for the first time, is the circumcircle of the Macbeath triangle. It has a fairly complicated radius, center function, and circle function, the latter two of which do not correspond to any Kimberling center. It passes through Kimberling center X_136 and the complement of X_933, which are its intersections with the nine-point circle.

central circle | Macbeath triangle

Alexander Murray Macbeath