C₂H(2−1) spectra towards the Seahorse IRDC clumps. The seven detected hyperfine components are labelled in the SMM 1 panel. The hyperfine structure fits to the lines are not shown to better see the detected lines. While the velocity range shown in each panel is the same (we note that it is much wider than in Figs. A.1–A.5), the intensity range is different to better show the detected lines. The C₂ H lines are seen in absoprtion towards SMM 5 and 6 (also towards SMM 7 but not at our detection limit of ≥ 3σ).