Kernels and galaxy distribution considered in this work. The first two plots show the kernels, or weight for the two photometric probes. The analytic expressions for these are, respectively, Eqs. (18) (left, WL) and (21) (right, GCph). At high redshifts, the IA term dominates over the shear term in the lensing kernels, making them negative. The rightmost plot shows the redshift distribution per redshift bin for the sources (and lenses), as well as their sum, obtained from the Flagship 1 simulation as described in Sect. 3.1.