Observed spectra of the CH₃CN 12–11 line toward the peak emission position of the A1 clump. The red line is the Gaussian fit results, and the residuals are shown right below the spectrum. The CH﹩{}_{3}^{\;13}﹩CN 12–11 spectrum is also shown in blue. Rotational diagrams of the K-components of the CH₃CN 12–11 line toward the A1, A2, and A5 peaks. Errors are 3σ of the observed uncertainties. Rotational temperatures are indicated for the A1 results.