Examples of μ(v) magnification profiles of C IV at four epochs (in red) computed from spectra of images A and B that were simultaneously recorded. The μ(v) profiles are binned into 20 spectral elements. The superimposed line profiles from image A (in blue) and B (in black) are continuum-subtracted, corrected for the macro-magnification ratio, and arbitrarily rescaled for convenience. The thicker line indicates the part used in the computation of μ(v). The error of μ(v) is shown in green. The observation date is given as yymmdd. The zero-velocity corresponds to the C IVλ1549 wavelength at the redshift z = 1.734.