Posterior probability distributions for the MCMC runs with the synthetic data. The dark orange colour shows a 68% and the light orange colour a 95% highest posterior density credible interval. In the 2D posterior distributions the solid contour shows a 95% and the dashed contour a 68% highest posterior density credible region. The blue crosses show the correct solution. The sin i prior in i is shown with a blue line. The compactness parameter u is defined here as u ≡ r_S/R_eq. The inset in the upper right corner shows the mass–radius posterior distribution in more detail.