Investigation of the discrepancy of the η Dra Hammersley et al. (1998) model and measured FIR photometry. For a better zoom-in over a large wavelength range, log₁₀ (λ⁴ × f_λ) is displayed. The red line is the model, absolutely calibrated at 2.208 μm (K_n magnitude = 0.62 ± 0.005 mag, c.f. Cohen et al. (1999), Selby et al. 1988) as represented by the violet square symbol. Dark-blue squares, light-blue diamonds, and green triangles represent IRAS FSC, PACS, and ISOPHOT HPDP photometry and their respective uncertainties. This photometry has been colour-corrected for a 5000 K blackbody spectrum.