Observed NH₃ (J, K) = (1, 1) spectra. In each panel, the green curve represents the fit to 18 hyperfine lines and the blue vertical lines under the spectrum indicate the positions of the 18 hyperfine lines and their relative strengths in the optically thin case under conditions of LTE. The red lines denote the integrated ranges used to calculate the HIA. The source name is labeled in the top-left corner of each panel.