Rotational temperature maps obtained by fitting CH₃CN (12_K−11_K) K = 0−6 and CH₃¹³CN (12_K−11_K) K = 0–3 lines with XCLASS. The contours correspond to the 1.37 mm continuum as described in Fig. 1. For NGC 7538IRS1, only the region outside the continuum to the south-west is modelled by XCLASS and was scaled towards the continuum peak position following a temperature power-law distribution T ∝ r^−0.4. The blue and red arrows correspond to the estimated directions of bipolar blueshifted and redshifted molecular outflows, respectively. The synthesised beam is shown in the bottom left corner and a scale bar in the bottom right corner of each panel. Maps of column density, velocity offset, linewidth, and source size are shown in Appendix E.