Another illustration of the degeneracy in our shock modeling. The gray histograms show the selected shock models for two pixels [−1, 4] and [−1, 2] that reproduce our CO and H₂ 0–0 S(3) observations within a factor of two (top and bottom; number of the selected models = 39 and 67, respectively). For each histogram, the final shock parameter we constrained in Sect. 5.3.3 is shown as the red solid line and summarized in the top right corner. A comparison between the top and bottom histograms clearly shows that [−1, 4] has a relatively narrow distribution of n_pre.