All isotomic central nK are centered on the Steiner circum-ellipse and always have only one real asymptote since they intersect the line at infinity on this Steiner ellipse. They form the class CL002 of cubics. See Special isocubics §3.4.3 and also Central cubics in the glossary. The general equation of these cubics is :
where (q - r : r - p : p - q) is the real point at infinity.)
The figure above shows K087, the central isotomic nK centered at X(99) with its real asymptote perpendicular to the Euler line. Compare K087 and K084.