Detected C₂H hyperfine structure lines of the N = 1 → 0, 2 → 1, 3 → 2, and 4 → 3 rotational transitions. The N = 2 → 1 transition was observed at 2 MHz resolution while the N = 1 → 0, 3 → 2, and 4 → 3 transitions were detected at 200 kHz. Hyperfine structure are only fully resolved in the N = 1 → 0 transition. The fine and hyperfine components are labelled with the quantum numbers J and F. For clarity, we have not included the labels of the transitions that were too weak to be detected.