Impact of stellar pseudo-signal on the transmission spectrum of HD 189733 b. Top: stellar master spectrum (black dots) with the modeled stellar spectra of bright (orange) and dark (blue) regions and both combined (dashed gray) for a filling factor of 0.8. Bottom: observed transmission spectrum in black. Average transmission spectrum caused by stellar pseudo-absorption (blue) signal. The dashed-dotted brown line is at the position of the Si I line and the dashed-dotted purple lines are at the position of the He I lines in the star (top) and planet (bottom) rest frame.