Absorption spectra of chlorine-bearing species observed toward MA0.89 SW (top three panels), MA0.89 NE (middle three panels), and MA0.68 (bottom panel). Hyperfine structure is indicated in green for ³⁵Cl-isotopologs of each line toward MA0.89 SW. Hyperfine structure was deconvolved by fitting multiple Gaussian velocity components; these fits are shown in red on top of spectra, with residuals shown in blue. On the right, deconvolved opacity profiles (assuming optically thin lines with f_c = 1, as explained in Sect. 3), normalized to their peak opacity, are shown, together with opacity profiles of some other species for comparison. The profile of p-H₂O⁺ is of the strongest hyperfine component of the 1₁₀–1₀₁ transition, at rest frequency of 607 GHz. The profile of o-H₂S is the 1₁₀–1₀₁ transition, at rest frequency of 168.8 GHz, which was observed simultaneously with o-H₂Cl⁺ in the same tuning.