Optical and infrared image of the field around cid_346, obtained by combining Subaru and Spitzer photometric data (see Table A.1). The images have been registered to the same astrometric solution, using the one with the best point spread function (z-band) as a reference. Known spectroscopic redshifts from the literature (blue) and photometric redshifts from Laigle et al. (2016) (red) are reported in the image. The red contours show the ACA CO(3-2) 1-3σ level emission from Fig. 1.