Selected J = 3–2 lines of HCN in various vibrational states (blue labels). The spectra observed with the IRAM 30-m telescope are indicated by black histograms. The line profiles calculated from our model (see text) are plotted in red. The line parameters are given in Table 1. Intensity scale is antenna temperature. Main beam antenna temperatures can be obtained by dividing the T_A ∗  scale of the 270 GHz data by a factor of 0.4. Velocity resolution is 2.3 km s^-1.