Using the Antennæ galaxy merger as a toy model to help visualise the background galaxy of H1429-0028. The two upper images show the F110W source-plane reconstruction from Fig. 8 (left hand-side) and the Antennæ galaxies as seen in the optical (right hand-side). The two bottom images show the CO (J:4 → 3) velocity-integrated flux source-plane reconstruction from Fig. 8 (left hand-side) and the CO (J:J^up = 1,2,3) map in the Antennæ galaxies as observed by ALMA. Image credits: NASA, ESA and Ivo Saviane (upper-right picture), ALMA (ESO, NRAO, NJAO; bottom-right picture).