Overview of data used in our analysis. We include transmission curves (left vertical, bottom horizontal axes) for the eight broadband maps used, from Spitzer, Herschel, and SCUBA-2. We overplot the rest-frame wavelengths of selected FIR emission lines, including [CII]-158 μm; these lines are redshifted into the broadband maps. The top horizontal axis labels translate the observer wavelengths into the rest-frame redshift z of a [CII]-158 μm emitter. We trace the z distribution of the COSMOS2020 photometric catalog (in bins of Δz = 0.05), with number counts on the right vertical axis; number counts for the selection of star-forming or quiescent emitters are also shown. Redshifted C+ emission will appear in the SPIRE maps for specific z ranges. Finally, at the top, we demarcate the z-binning used for stacking with LinSimStack; bins at z ∼ 0.65, 1.3, 2.1, and 2.6 were chosen to overlap with the SPIRE bands.