Dust continuum maps of the QSO field with different resolutions. Left panel: dust continuum map of the QSO field centred on the phase-tracking centre of the observation. Levels are −3, −2, 2, 3, and 4σ, σ = 8.8 μJy beam⁻¹. The cross indicates the phase centre. In this map the QSO is located at offset [6, −2] arcsec. Central panel: zoomed view towards the phase centre. The clean beam is plotted in the lower left corner. Right panel: 260 GHz dust continuum uv-tapered map of Serenity-18 (levels −4, −3, −2, 2, 4, and 5σ, σ = 15 μJy beam⁻¹). The imaging has been performed with uvtaper = [0.5 arcsec]. The clean beam is indicated in the lower left corner. The black cross indicates the position of the phase-tracking centre, which coincides with the expected position of the CO-emitter Serenity-18 (D’Odorico et al. 2018). The white cross indicates the continuum emitter detected in the beam (see text).