Published online by Cambridge University Press: 25 April 2016
Following the detection of the 9 cm ground-state triplet of CH by Rydbeck et al. (1973), preliminary observations at the CH frequencies were made with the Parkes 64-m telescope (beamwidth ∼6′ arc) in December 1973 and January 1974. We have detected the CH lines in many galactic HII regions and in the direction of the galactic centre.