Zoom-in on the stacking outputs for the Herschel/SPIRE 250 μm COSMOS map, illustrating our forward modeling LinSimStack methodology. Left to right: 2D vectors for the data d, model m, and the residuals r = d − m. The model m is a linear combination of all beam-convolved hit-maps constructed using the COSMOS2020 photometric catalog. We also plot sources from the Herschel/SPIRE Point Source Catalog (HSPSC) with estimated fluxes in the HSPSC above 30 mJy, which correlate with the residual flux in the 2D vector r (see Section 3.4, Appendix A, the corresponding figures, and the discussion for further details on model incompleteness).