CLV observations and their inversion. Top row: measured brightness temperature as a function of reference μ, for commissioning data and from the current data set. Middle row: normalized data set. The solid line shows a third degree fit and the dash-dotted line shows a linear fit up to log μ₁₀₀ = 0.8. Bottom row: electron temperature as a function of the reference optical depth, deduced from the inversion of the observations. Model curves from Fontenla et al. (1993) and our results from Paper II are also plotted.