Model fits to the flux at 5.7 μm from ejecta observed in the nucleus-centered 9.25′′  ×  9.25′′ extraction. Fluxes are normalized to the value measured at TI + 3.6 h. Data are shown with filled symbols with error bars. Results from a time-dependent dust model considering a short-duration (1000 s) outburst are shown both for a power-law size distribution a) and a Hanner distribution b) for amorphous carbon grains (solid line) and two-layer grains (dashed line). Black lines are for the best slope of the velocity distribution q_v, green lines are for q_v + 0.05 and red lines are for q_v − 0.05. The value of v_ref = 230 m s^-1.