Ro-vibrational plots (Boltzmann plots) of the H₂ lines from knots C1–17, with full JHK coverage. Open black squares mark transitions from the upper vibrational level v = 1, open red circles transitions from v = 2, open blue triangles transitions from v = 3, and full black triangles upper limits for various undetected transitions. The straight lines mark the best linear fits obtained for both the excitation temperature and the extinction simultaneously. The data displayed have been corrected for the extinction value providing the best fit. The obtained temperature, extinction, and reduced χ² are also indicated in each panel.