Posterior distributions of the model parameters from the MCMC fit. Diagonal panels show marginalized one-dimensional posteriors; off-diagonal panels show two-dimensional projections that reveal covariances. The ¹²C/¹³C and ¹⁸O/¹⁷O ratios are tightly constrained and largely uncorrelated with other parameters, whereas ¹⁶O/¹⁸O and ﹩\mathrm{log}{N}_{{\rm{CO}}}﹩ exhibit strong covariance, reflecting the moderate optical depth of C¹⁸O(1–0).