The velocity-equivalent residuals from wavelength -calibrating synthetic data which are modeled after NRES, for three levels of velocity-equivalent Gaussian centroid errors (﹩{\sigma }_{v,\mathrm{in}}﹩): 10 cm s⁻¹, 1 m s⁻¹ and 10 m s⁻¹. In each panel, the injected error ﹩{\sigma }_{v,\mathrm{in}}﹩ is shown near the top left, and the error estimated from the residuals after calibrating the spectrum, ﹩{\sigma }_{v,\mathrm{out}}﹩, is shown below it. To the right of each panel, we have plotted a Gaussian with zero mean and standard deviation ﹩{\sigma }_{v,\mathrm{in}}﹩ on top of the histogram of residuals.