Selected lines of CH₃NCO as observed with the IRAM 30 m radio telescope (toward the IRc2 source at α_2000.0 = 5^h35^m145, δ_2000.0 = −5°22′30.′′0, 0.5′′north to source I, see Fig. 3) and the ALMA interferometer (Position A, see Fig. 3). The red lines show the model of CH₃NCO emission discussed in the text. Red labels show the quantum numbers of the corresponding lines. Blue labels show the species responsible for the other features observed in each panel. The complete set of detected lines of CH₃NCO is shown in Fig. B.1. The intensity units for the last four panels (ALMA data) are in Jy/beam. They can be transformed into brightness temperature, T_B, by multiplying the intensities by a factor of 9. The intensity scale for the 30 m IRAM telescope is the main-beam antenna temperature in K.