ALMA Large Programme detection example. Left panel: Full ALMA pointing for Q0454−220 quasar field. The purple star marks the position of the background quasar labeled QSO. Middle panel: Zoomed-in view of the CO(2–1) detection corresponding to the z_abs = 0.4833 absorber. The synthesised beam is indicated by the hashed area in the bottom left corner. Right panel: Corresponding ALMA spectrum displaying the flux emission at the expected frequency at 155.77 GHz. The detections of the full sample are reported in Bollo et al. (2026).