Analysis of the observed ketene transition. Left: moment 0 map at 260.192 GHz. The contours start at 4σ at every 2σ. The ellipse in the bottom left corner represents the ALMA synthesised beam (0.44″ × 0.37″). Sources A and B identified by Alves et al. (2019) are indicated as filled white circles. Right: H₂CCO transition at 260.192 GHz. The red line corresponds to the modelled transitions as described in Sect. 5. The grey shaded area corresponds to the filled histogram above and below the baseline.