X(2), X(4), X(193)
vertices of the orthic triangle
points at infinity of the Thomson cubic.
It is tangent at A, B, C to the medians and at H to the Euler line.
It meets the circumcircle at the same points as the isogonal pK with pivot X(3060). (green curve)
K181 is the locus of point P such that the trilinear polar of P is perpendicular to the line PH. See CL040 for a generalization.