Spectrum of the giant star CS 29491-053 ([Fe/H] = –3.0) in the region of the S I lines of multiplet 1 (wavelength in nm). The synthetic spectrum (red line) has been computed for the adopted abundance (Table 3), and for an abundance 2.5 times smaller (thin blue line). The S line at 922.8 nm lies in the wing of the hydrogen line Pζ; all other lines in this region are of telluric origin. In our analysis, all S lines blended with telluric lines have been rejected.