Primary beam of individual mosaic pointings (blue circles) of the NOEMA observations for SWAN overlaid on a map of the integrated intensity of HCN(1−0) emission (left) and ¹³CO(1−0) emission (right). Contours represent integrated N₂H⁺ emission at 0.5 and 2 K km s⁻¹. The pointings shown have a radius of ∼28″ (HCN) and ∼22.5″ (¹³CO, our highest frequency detected line). We interpolate the outer edges of the individual mosaic pointings to define the area inside which we measure the integrated flux of each observed emission line (red line). Because the primary beam changes with frequency, so does the area used to calculate the line flux.