Best agreements obtained between data (scaled opacities between 200 and 300 km) and model for each observation. Good fits (blue line) can be obtained for any fractal dimension between 1.8 and 2.5, albeit with different values of N and κ. All these fits are superimposed (only cases between D_f = 2 and 2.5 are reported here). The green line shows the opacity slope for aggregates with N = 3000 and D_f = 2.0, as in Tomasko et al. (2008). This plot and Fig. 6 show that this structure of aggregates can be discarded.