Example of a spline used to rescale SL in the case of HS 1304+3529. The diamonds represent the ratio between the observed and the synthetic photometry. The spline has been fitted to the blue diamonds, except at 5.8 μm where the galaxy is not detected. The black curve is the final adopted spline, sp(x₀), where x₀ = 1.9. The orange crosses are the corrections applied to the SL part of the spectrum.