Radiative-transfer models (lines) compared with observations of Betelgeuse. The blue triangles show fluxes, taken from Vizier (listed in Table A1 in the Appendix), and the green, red, and purple points indicate the data from this work in the same color scheme as Figure 1. The blue dashed line represents a qualitative fit from HYPERION to the 0.3–30 μm photometry, and the orange dotted line a model that is identical other than the addition of an extra shell of dust from 2 to 4R_* that produces 1 mag of V-band extinction and the gray solid line shows the underlying photospheric model at the same spectral resolution as the radiative-transfer models. The inset panel highlights the sub-mm fluxes from this work and the model flux in the same region.