Confirmed species detections in KELT-9 b. Each panel presents each species’ 2D and 1D cross-correlation signatures in the following order: H I, Na I, Mg I, Ca II, Sc II, Ti II, Cr II, Fe I, Fe II, and Y II. In the K_p – V_sys maps, the white dashed lines locate the maximum peak of the signal. One-dimensional cross-correlation functions are extracted from the K_p – V_sys map by selecting the row of pixels at the maximal location of the signal. The dashed dot represents a Gaussian fit to the cross-correlation function, and the vertical dotted lines mark the location of the peak for each example. The blue-shaded region represents the standard deviation of all points away from the peak of each function.