Observed-frame 870 μm ALMA images towards AzTEC/C1–C27. Each image is centred on the ALMA 870 μm peak position (except the non-detections (AzTEC/C1b, C8b, C10c, and C13b), which are centred on the ALMA 1.3 mm position), is in size, oriented such that north is up and east is left, and displayed in a common linear colour-scale. The contour levels start from 3σ, and progress in steps of 3σ. The detection S/N_{870 μm} ratio is indicated in parenthesis. The white and magenta ellipses show the deconvolved FWHM source sizes at 870 μm and 3 GHz (the present study and M17a, respectively). The ALMA synthesised beam FWHM is shown in the bottom left of each panel.