Spectra of SO J = 2₃ − 1₂ at 99.3 GHz, SO J = 3₂ − 2₁ at 109.25 GHz, and SiO J = 2 − 1 at 86.85 GHz towards a position in the red-shifted lobe (N1NW3, top row), N1S (middle row), and a position in the blue-shifted lobe (N1SE1, bottom row). The black dashed lines mark the systemic velocities of 64.8 km s⁻¹ (N1NW3), 62.2 km s⁻¹ (N1S), and 63.6 km s⁻¹ (N1SE1), while the dashed blue and red lines indicate the inner and outer limits used to integrate the blue- and red-shifted emission shown in Fig. 2. While the outer limits are fixed values, the inner limits are pixel-dependent and set such that channels that contain absorption features close to the systemic velocity are excluded.