[CII] coverage for our sources. Left column: spectra extracted at the position of our targets. The dashed and dotted green lines are, respectively, the expected ν_obs, [CII] and its uncertainty. The red curves show the MPFIT Gaussian fits at fixed frequency and FWHM. Channels where a significant contribution from Hyde could be expected were masked, as shown by the grey vertical area. Right column: dirty images averaged over the stellar FWHM of our sources: ZF-COS-20115, before and after Hyde’s subtraction (top two panels); ADF22-QG1 (mid panel); GS-9209 (bottom panel). The positions of the QGs are shown as black crosses. The contours show 1, 2, 3, and 4 times the rms of the image.