CO(2–1) observations of P036+03, J0305–3150, and J2348–3054 (from top to bottom, respectively). Left: Cleaned channel maps with the middle panel depicting the moment-0 map centred on the [C II] 158 μm redshift and integrated over 1.2× FWHM of the [C II] 158 μm line, which should encompass 84% of the CO(2–1) emission assuming there is no spatial or velocity offset. Right: Observed CO(2–1) spectra extracted from the pixel at the peak position of the moment 0 maps (blue line) and 1σ rms per channel (orange line). The spectra are shown for channels of 100 km s⁻¹ velocity width, the shaded region indicating the 1.2 FWHM region used to create the channel maps to the left. P036+03 and J0305–3150 are undetected (with a significant number of negative and positive peaks in the data cube exceeding the significance of the peaks in emission near the expected source centres), so we place 4σ upper limits on their CO(2–1) emission. J2348–3054 is detected at 5.1σ (central velocity-integrated map in bottom row).