Four circumstellar extinction curves were estimated with DUSTY using an MNR distribution and dust sizes from 0.005 to 0.25, 0.45, 0.75, and 2.00 μm, respectively. The curves are normalized to 9.7 μm in the left panels and 2.12 in the right panels. The astronomical silicate grains by Ossenkopf et al. (1992) for a maximum grain size of 0.25 μm (black), 0.45 μm (orange), 0.75 μm (cyan), and 2.00 μm (green) are used in the two upper panels; while in the two lower panels the silicate grains of Suh (1999) are used. The squares mark the circumstellar effective extinction ratios measured on SED models generated with the DUSTY code. The curves are obtained by interpolating the ratios to a finer grid (0.1 μm).