Doppler residuals for the “synthetic” SPICE data made from IRIS observations. Residuals are compared with data with the “nominal” symmetric SPICE PSF and detector scale applied – free of the PSF artifacts. Panel a: Original IRIS amplitude (for context). Panel b: Magnitude of the difference between the corrected Doppler and the Doppler with only the “nominal” symmetric SPICE PSF and detector scale applied. This image is free of PSF artifacts and looks essentially identical to panel a of Fig. 13 except for the smaller pixel size, so it is not shown. Panel c: Difference between the uncorrected Doppler and the same nominal Doppler in panel b. Except for areas with a very low signal (see panel a), the corrected Doppler is within 3 km s⁻¹ of the nominal, whereas the uncorrected Doppler is essentially above 3 km s⁻¹ everywhere.