Excitation diagrams of observed H₂ line column density distribution as a function of upper energy level. The column density is normalized to the 1-0 S(1) H₂ transition. Diamonds represent lines from v = 1 while the asterisks represent points from v > 1. The solid line is a best fit of the Boltzmann distribution to the v = 1 points, the slope represents the excitation temperature, T_ex. Each panel represents a different region, corresponding to the regions in Fig. 5. The error bars represent a standard deviation from the column density.