Planetary spectrum blurring in the stellar template. Using our synthetic spectra of HD 217107 b we simulated the smearing of the planetary spectrum over one observing run. The dark-gray and light-gray lines denote the first and last spectra of HD 217107 b during an observing night. The relative shift owing to the orbital motion of HD 217107 b is 40 km s^-1 in this simulation. The bottom black line shows averaged the planetary spectra.