NH₃ (1,1) and (2,2) spectra at offset (Δl, Δb) = (2′, 16′) with respect to the reference position (l = 28.59°, b = 3.55°). In each panel, the black solid line represents the observed spectrum, the green solid line indicates the NH₃ (1,1) fitting (lower panel) and Gaussian fitting (upper panel) of the NH₃ (2,2) line (see Sect. 2.2). The groups of hyperfine components “mg”, “isg”, and “osg” represent the main, inner-satellite, and outer-satellite groups. The velocity scale is Local Standard of Rest, here and elsewhere.