At 20h44 UT, the (Fiber B/Fiber A) ratio (solid line) is shown in the NaI doublet spectral region. The Fiber A spectrum (dashed line) with its corresponding zero level (horizontal dashed line) as extracted from the SOPHIE pipeline as well as an H₂O model (dotted line) are overplotted (in arbitrary scales simply to fit within the figure frame) to show the positions of the solar as well as H₂O spectral lines in the spectrum. Most of the observed lines are due to atmospheric water vapor. They disappear in the fiber’s spectral ratio, while the broad spectral wings of the two NaI solar lines are still clearly visible.