Variation of the Fe I 6301.5 Å (upper panel) and Fe I 6302.5 Å (lower panel) line shapes from the disk center (μ = 1.0, purple line) toward the solar limb (μ = 0.3, with decreasing gray scale). The intensities of the profiles were normalized to the spectral continuum and are plotted against the air wavelength (in Å). The FTS atlas profile is added in yellow for direct comparison. The line minimum at μ = 1.0 is marked by the dotted line.