Fit to the flux for L_avg = 8500 L_⊙ and effective temperature of 2300 K is shown in both panels by black solid line. The contribution from the central star is shown in the bottom panel by the dash-dotted magenta line. SWS and LWS ISO spectra are shown by red dotted lines. Photometric data below 1 μm are from GSC 2.3, those between 1.25 and 5 μm are from Le Bertre (1992) at three different phases: 0.02 (stars), 0.21 (filled squares) and 0.23 (dotted squares), while at longer wavelengths the flux is from IRAS (crosses) and COBE DIRBE (x) measurements. The dust model obtained for L_max = 11 850 L_⊙ is shown by dashed lines on each panel (see text for details).