Distribution of the main spatial HCN J = 1 → 0 features with integrated HCN intensity as background. Assigned numbers are also presented in Col. 2 of Table 2, together with additional information. This includes the offset from position 9, the peak of the λ ≈ 3 mm continuum emission (see Fig. 1), which is responsible for the absorption features seen in most spectral lines. For the three quadratic areas surrounded by white dashed lines, see Sect. 3.2.5. The value 1″ corresponds to a projected linear scale of ≈19 pc. The beam size (2.′′71 × 1.′′ 56, position angle 43°) is given in the lower left.