UltraVISTA Y-band (λ_eff = 1.02μm) images towards AzTEC2, 5, 6, 9, 10, 13, and 17a shown in linear scale. All the images are 15″ on a side. The white rectangles indicate the DEIMOS slit positions, sizes, and orientations (see Table E.1). We note that all the slits were aligned horizontally along the east-west direction. The central position of the slit is marked with a white plus sign, while the green circle of radius shows the SMA 890 μm peak position (Younger et al. 2007, 2009) except in the case of AzTEC17a where it marks the PdBI 1.3 mm peak position. The red circle in the AzTEC6 panel represents the optical galaxy discussed by Koprowski et al. (2014); see Appendix B for details.