Scale length and effective radius. The fit exponential scale length, l⋆, divided by the effective radius, Re, measured from the same profile. The black dashed line shows expectations for a pure exponential disk (Equation (4)). Points above this line show some central concentration compared to a pure exponential disk, and this central concentration drives Re to smaller values. The l⋆ fits should better capture the exponential portion of the profile. The axes are correlated, and the detailed trend is less important than the qualitative point: that many galaxies with small Re have bright nuclear concentrations, and that the fit l⋆ indicates a much larger disk in some of these cases. That larger l⋆ will be the relevant quantity for disk structure calculations or metallicity gradient estimation.