Investigation of the discrepancy of the β Gem Cohen et al. (1996) model and measured FIR photometry. For a better zoom-in over a large wavelength range, log₁₀ (λ⁴ × f_λ) is displayed. The orange and red lines are the Cohen et al. (1995) absolutely calibrated 1.2–35 μm spectral model and the Cohen et al. (1996) FIR extension, respectively. The black line represents a scaled (×0.169) fiducial star continuum model of α Boo (Dehaes et al. 2011). The scaling factor has been derived from the Selby et al. (1988) K_n narrow bandphotometry ratio 10^{−0.4×(−1.14 + 3.07)} and the position of the scaling wavelength (2.205 μm) is indicated by the violet square symbol. We note that the K_n zero point is ≈3% higher than that for the Cohen models (cf. file header of α Boo model (reference, see text) vs Table 1 in Cohen et al. 1992). Dark-blue squares, light-blue diamonds and green triangles represent IRAS FSC, PACS and SPIRE photometry and their respective uncertainties. This photometry has been colour-corrected for a 4500 K blackbody spectrum.