Combined (three nights) residual spectra in the planetary rest frame centered at the 10 830 Å He I line. In the three panels, the solid black line indicates the residual spectra, boxcar-smoothed by 3.7 km s⁻¹ (top), 14.9 km s⁻¹ (middle), and 29.8 km s⁻¹ (bottom). The dotted curves show an artificially injected signal at an S/N of 5, and the solid red curve shows the difference between the injectedand original data. The values are scaled by the standard deviation of the observed residuals so that the y-axis represents the S/N.