SSP luminosity evolution ℓ_λ,IMF(t_∗) as SFH sensitivity curve (i.e., after normalizing to the integral of the SSP over the age of the system, 13 Gyr in our case). The left panel shows the sensitivity curve on a linear scale from 0 to 10⁷ yr, the right panel the sensitivity curve on a log-log scale for the whole age range. In descending order at young ages the curves correspond to Q(H), galex/FUV and NUV, and sdss/u, g, r, i and z.