Isolated component of N₂D⁺ (1–0) (left panel), the central component of N₂D⁺ (2–1) (centre), and the N₂D⁺ (3–2) line (right panel). In each panel, the horizontal dashed lines are the observed peak temperatures of the selected N₂D⁺ transition at the dust peak (red), and at 40″ of offset (green). The shadowed areas represent observational uncertainties. The solid curves indicate T_MB as a functionof T_ex, obtainedvia the radiative transfer equations and using the column density values predicted by MOLLIE at the two offsets. The vertical dashed line is the T_ex value used in the analysis of the maps, and the grey shaded area is its uncertainty (0.5 K).