Red variant CCD91-72 across-scan line-spread function for sources with 20 e⁻ (top) and 1.5 e⁻ (bottom) per HR sample (i.e. integrated over the line profile) corresponding to V = 11.9 and 14.7, respectively, as a function of number of serial register transfers. This profile assumes the nominal optical performance, but no across-scan broadening from distortion or the forced precession in the scan law. From Chassat (2009).