Spectra of the Ν = 1, J = 3/2 → 1/2 transitions of CD and CH. Top panel: filled grey histograms represent the normalised spectra of CD at 439 260 MHz (left) and 439 800 MHz (right) observed towards IRAS 16293–2422 alongside the GILDAS-Weeds model fit overlaid in red. The relative intensities of the HFS splitting components are marked in blue. Unidentified, contaminating spectroscopic and/or baseline features are labelled- U? in light blue. Bottom panel: same as the top panel but displaying the corresponding CH spectra at 532720 MHz (left) and 53 6780 MHz (right), respectively.