Example of wavelength alignment of observed and template spectra for radial velocity determination. The observed spectrum (gray) and the viscous model spectrum (orange) with $M_{\ast }\dot{M}={10}^{-4.5}{M}_{\odot }^2$/yr, $sini\sqrt{M_{\ast }}=0.02\sqrt{M_{\odot }}$, R_in = 3.5 R_⊙, and R_out = 270 R_⊙ are continuum-normalized and shown over the wavelength range 2.2850−2.3200 μm, covering the CO Δv = 2 (2−0) absorption band. The observed spectrum after applying the radial velocity correction derived from the cross-correlation analysis is shown in blue. The inset displays the CCF as a function of radial velocity, with the dashed red line indicating the velocity corresponding to the maximum correlation.