Distribution of the difference between the ThAr wavelength solution and the LFC wavelength solution, evaluated for each point in all orders. The LFC solution is based on a 2D polynomial. There are more outliers beyond the limits of the histogram, which are not shown here. The orange dashed line, shows the Gaussian with the same mean and standard deviation as the whole distribution. Left: 1D ThAr solution, right: 2D ThAr solution.