Reduced χ² parameter space for the two frequencies. The points have been colour-coded with dark blue and dark red representing lower and higher reduced chi-square: 2.06 ≤ χ² ≤ 6.50. The solutions with e ≥ 1.0 were excluded since their solutions will give parabolic and hyperbolic orbits. The grey star marks the location of the solutionadopted in Paper I, whereas the red circle and magenta cross mark the solution with the lowest reduced χ² adopted as the best-fit for this paper.