Top left: CCF of CT Cha b on-sky data on 1SHORT, calculated with a BT-Settl template at 2600 K Doppler shifted with 13.5 km/s and R_c = 100 (the S/N color scale is cropped to ±5). Top right: histogram of the CCF. Bottom left: contrast curves calculated analytically using FastCurves are shown in red, assuming t_exp = 56 min, K_* = 8.7, and the same planetary spectrum used to compute the CCF. The solid red curve represents the result including both fundamental and systematic noise (${\sigma }_{\mathrm{C}\mathrm{C}\mathrm{F}}^{\mathrm{F}\mathrm{C},\text{fund}+\text{syst}}$), while the dashed red curve represents only fundamental noise $\left({\sigma }_{\mathrm{C}\mathrm{C}\mathrm{F}}^{\mathrm{F}\mathrm{C},\text{\hspace{0.17em}fund\hspace{0.17em}}}\right)$. Empirical contrast curves derived from on-sky data are shown in blue, where the solid blue curve corresponds to the spatial standard deviation of the CCF (${\sigma }_{\mathrm{C}\mathrm{C}\mathrm{F}}^{\text{spatial}}$), and the dashed blue curve corresponds to the errors estimated from the ERR extension values (${\sigma }_{\mathrm{C}\mathrm{C}\mathrm{F}}^{\mathrm{E}\mathrm{R}\mathrm{R}}$). Bottom right: analytical contrast contributions.