Test on B₁ measurements chromaticity. Shown are B₁ measurements obtained with line mask subsets based on wavelength of the optical (circles) and near-infrared (pluses) domain. The horizontal black lines indicate the values of B₁ computed with the full masks and the vertical dashed line separates arbitrarily optical from near-infrared measurements. The error bars are smaller than the symbol size. For visualisation purposes, the [350, 390] nm wavelength bin is not shown since it leads to an outlier data point at around −1 kG, and the [390, 430] nm bin yields a value at −750 G so it is indicated with a downwards arrow. Overall, no chromatic trend emerges from the data.