LVG analysis of CH₃CN in the S68N outflows. Panels (a) and (b): Density–temperature χ² contour plot (a) and reduced χ² versus N_CH3CN plot (b) for R1 (orange) and R2 (red). In panel (a), the contours represent the 1σ confidence levels, and the best-fit solutions for R1 and R2 are marked by orange and red stars, respectively. Colour coding matches that of Fig. 1. Panels (c) and (d): Same as (a) and (b), but for the blue-shifted regions B1 (blue) and B2 (cyan).