Comparison between the isolated hyperfine component of o-NH₃(1₀ − 0₀) (filled grey histogram); for clarity, the NH₃ spectrum has been cut above 7.8 km s^-1 (6.6 km s^-1 in the velocity scale of Fig. 1), where the other groups of hyperfine components are present and other molecular lines observed toward the same position: C¹⁸O(1−0), o-H₂D⁺(1₁₀ − 1₁₁), N₂H⁺(1−0), HCO⁺(1−0), and o-H₂O(1₁₀ − 1₀₁)  (thin histograms). To allow a clearer profile comparison, the C¹⁸O(1−0), o-H₂D⁺(1₁₀ − 1₁₁), N₂H⁺(1−0), and HCO⁺(1−0) spectra have been divided by the numbers shown below the transition in the top left corner of the panels. In the case of o-H₂O(1₁₀ − 1₀₁)  (last panel on the right), the spectrum has first been multiplied by 4.5 and then shifted by +67 mK. The comparison spectra are in order of increasing optical depth, from left to right. The vertical dotted line marks the core velocity.