Illumination of the circumbinary disk by an effectively point source located at the compact object. The azimuthal angle is measured from the line connecting the companion with the compact object; thus intensity 1 at azimuthal angle 0 degrees corresponds to illumination of that patch of the circumbinary ring closest to the compact object. The illumination pattern rotates round the ring with a period of 13.08 days. The wider distribution corresponds to a geometry for equal masses with the orbital radius of the compact object A/2 and of the circumbinary ring 2A. The narrower corresponds to a radius of the ring orbit 1.6A and a somewhat smaller mass ratio. Both geometries are plausible.