Fitting results for the colour excess ratio in H band. Left-hand side panels: filtered source distribution in a greyscale scatter plot, where the greyscale is proportional to the number density in this parameter space. The thin blue contours refer to 0.5, 10, 40, and 80% of the maximum source density. Also plotted is the resulting fit as the orange dashed line. Right-hand side panels: posterior probability distribution for the intercept α_H and the slope β_H (the colour excess ratio). The ellipses are the 1-, 2-, and 3-sigma covariances of the distribution. Projected to the top and to the right are normalized kernel densities of the resulting distribution for each parameter. The differently shaded filled areas under the curve highlight the 1-, 2-, and 3-σ ranges.