Rotational diagrams of J = 1 → 0, J = 2 → 1, J = 4 → 3, J = 6 → 5, and J = 8 → 7 transitions of ¹³CO at Her 36. Shown in black is the rotational diagram when ¹³CO is assumed to be optically thin. In red the rotational diagram is shown including the optical depth correction factors. Rotation temperatures obtained from different slopes are indicated. Values of the velocity integrated intensities for different transitions were extracted from maps convolved to the same resolution of 31′′. The error bars were calculated from the maximum noise level of the integrated intensities of individual transitions and from calibration uncertainties of 20%.