Calculating the lower limits on redshifts for sources 8 (left) and 16 (right), both of which are detected at 850 μm and at no other wavelength in this study. Using the 5σ detection thresholds (marked as downward pointing arrows) at optical through to FIR wavelengths, and the detection at 850 μm, we redshift the Michałowski et al. (2010) template SED until it lies below the limiting fluxes. In this way we determine limits of z = 5.4 and z = 4.7 for sources 8 and 16, respectively.