Simulated spectrum of a typical galaxy (in terms of mass and star formation rate) from the Euclid weak lensing population at z = 1 (D. Masters, priv. comm.), overlapping the I_E, Y_E, J_E and H_E bands. The Vera C. Rubin Observatory photometric bands (u, g, r, i, z, y) are also shown, highlighting the importance of the ground-based data to the photometric redshift derivation as the 4000 Å break falls within the i band. The total sensitivity for the ground is given at 1.2 airmass.