Top left: ALMA Band 4 continuum image. The white box indicates the FOV of the Band 7 image. All six sources are labeled with their primary-beam-corrected fluxes in parentheses. Top right: ALMA Band 7 continuum image, with primary-beam-corrected flux densities in parentheses for the five visible sources. The location of the SDSS J0909-0108 post-starburst galaxy (z = 0.7021) is marked by an X in both images. Middle: HSC i-band cutouts of each source overlaid with ALMA Band 7 (red) and Band 4 (blue) contours at 3σ, 5σ, and 7σ. Lower left: spectra for each source in the Band 4 upper and lower sidebands. The blue vertical lines mark the frequencies of the two line candidates found in source 6. Lower right: spectra for each source in the Band 7 upper and lower sidebands.