Upper left: spectrum of the total integrated CO(2–1) emission for ESO 420-G13. Bottom left: spectra of the integrated flux for two pseudo-slits extracted along the kinematic minor axis, one intersecting the outflow (1″ <  Δx <  3″, orange dot-dashed line) and one in the opposite direction (−3″ <  Δx <  −1″, dotted blue line). The CO(2–1) flux extracted from a 3D mask applied to the ALMA datacube allows us to isolate the outflow emission (solid red line) from the rotating gas. A symmetric mask located south-east of the nucleus at blueshifted velocities has also been applied, although no counter-outflow is detected in the integrated spectrum (dashed purple line). The negative amplitudes at ∼−70 km s⁻¹ are produced by interferometric artefacts in the image reconstruction process. Right: pseudo-slit positions (dashed blue and dot-dashed orange rectangles) and the projections of the outflow mask (solid red contour) and the counter-outflow mask (dashed purple contour) are indicated in the mean velocity map.