The filled circles show the populations without any extinction correction. Using this method for the other sources with more than four lines detected, we also derive a visual extinction of 30. Nevertheless, a visual extinction of 30 mag is in agreement with the average foreground extinction as measured by Catchpole et al. In the other sources where we cannot estimate the extinction from our data we have applied a correction of mag. The filled circles are connected when more than three lines are detected.
Arrows indicate upper limits.
Current data do not show any evidence for a non-equilibrium OTP ratio, but we cannot rule it out a priori. In this case, the extinction would be of 20-25 mag instead of 30 mag. On the contrary, assuming OTP ratios of 1 one finds, in general, rather artificial diagrams, which suggests that OTP ratios as low as 1 are not compatible with the data. There is no clear dependence of T 32 on the distance to the Galactic center. However, it is noteworthy that the two clouds with lower T 32 are located in the Sgr C complex, one of them in the non-thermal filament.