χ² hypercube projections on the (p,Log₁₀(Σ₄₀)), (p, R_out), and (Log₁₀(Σ₄₀), R_out) planes, to produce each plot we have chosen the value of the other parameters corresponding to the minimum of χ² at each position on the planes shown. Contours represent the 68% and 95% confidence levels for the fit. In each row we show the results for the fit at a given wavelength, from top to bottom ar 0.87 mm, 1.3 mm, 2.7 mm and 7 mm (as labelled to the right).