HST/WFC3 F105W (left) image of AzTEC-3 overlaid with source positions, ALMA 850 μm continuum map (center), and SMG subtracted map (right). The continuum maps were created using line-free channels. The residual map was produced following the steps described in Sect. 3.3.2. The original continuum image contours are shown at −3, −2, 5, 10, 20, 30, 40, 50, 60, 70, and 80σ levels. The subtracted image contours are shown at −3, −2, 3, 4, 5, 6, and 7σ levels. Synthesized beams are shown in the bottom left of the ALMA images.