Calculated OPR of NH₂ computed as a function of temperature for a density of n_H = 1 × 10³ cm^-3 for translucent sources. Shown are OPR values for thermal equilibrium and Models 6–7 at assorted times. The hatched boxes represent the OPR measurements from Persson et al. (2016) within their formal errors, for the translucent gas towards W31C found at three different gas velocities. The dotted horizontal lines with arrows mark the lower limits in the translucent gas towards W31C in blue and W49N in pink. The temperature range is limited to 5–35 K even though the observed ranges can be as large as 100 K. See text.