Spectral properties for our set of models. Comparison of the observer’s frame luminosity in the UV and optical ranges for our set of models with an interaction power covering from zero to 10⁴³ erg s⁻¹ and at a time of 41.76 d. The inset zooms on the Hα region. The thick vertical line represents the rest wavelength of Hα, and the thin vertical lines indicate the wavelength at ±11 700 km s⁻¹ away from that rest wavelength.