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 
and the complement of
, which are its intersections with
the nine-point circle (P. Moses, pers.
comm., Feb. 8, 2005).
