Examples of photometric evaluation of the incident spectra created in this work. Top: one incident spectrum from the L16 catalogue compared to observational data from HST photometry (purple diamonds). Bottom: one incident spectrum from the Β19 catalogue compared to observational data from the SHARDS survey photometry (black diamonds). The blue line shows the spectrum resulting from the combination of the continuum, obtained using the library of evolutionary stellar population synthesis models GALAXEV (Bruzual & Chariot 2003) with our predicted emission lines. Top right: zoom on the Hα-[N II]λλ6584,6549 that highlights the typical emission line broadening due the velocity dispersion calculated using the relation presented by Bezanson et al. (2018). The red diamonds indicate the integrated fluxes that we obtained by convolving the spectra with the Euclid I_E, Y_E, J_E, and H_E filters.