Corner plot obtained from the RADEX/MCMC exploration for CH⁺, taking into account all detected rotational and ro-vibrational transitions. The diagonal panels show the marginalized posterior probability distributions of Tkin (linear scale), n(e⁻), n(H), and N(CH⁺) (log₁₀ scale), while the off-diagonal panels display the corresponding pair-wise correlations. The orange lines and markers indicate the maximum posterior estimate, and the vertical dashed lines in each diagonal panel mark the 16th and 84th percentiles (i.e., the 1σ credible intervals). The contours in the 2D panels enclose 39.3% and 86.4% of the posterior probability, corresponding to the 1σ and 2σ confidence regions for a two-dimensional Gaussian distribution.