X(2), X(6), X(15), X(16), X(55), X(385), X(672), X(5638), X(5639)
vertices of the Thomson triangle Q1Q2Q3
6 feet of bisectors
6 points on the medians such as (±a^2;bc,bc)
L1, L2 on the Lemoine axis, on the Parry circle
extraversions of X(55), X(385), X(672)
Q090 is the isogonal transform of the Stothers quintic Q012. It is a nodal quartic with node K. The tangents at A, B, C, Q1, Q2, Q3 pass through K.
It is related to nodal cubics inscribed in the Thomson triangle.