Posterior probability and covariance distributions of the flare-emission model parameters. Panel a: hydrogen column density, plasma temperature, X-ray intrinsic luminosity in the 2−8 keV range, and equivalent width of the Fe line at 6.4 keV. The size of the MCMC samples is about 4.6 × 10⁷ with about 4.5 × 10⁴ independent MCMC samples. The dashed and dotted vertical lines in the diagonal plots show the median value and the 90% confidence interval (C.I.) for each parameter. The contours in the other plots are 11.8, 39.3, 67.5, and 86.5% C.I. (corresponding to 0.5, 1, 1.5, and 2σ levels for a 2D Gaussian) for each pair of parameters. Panel b: alternative last row with count number from the emission line.