The χ² curve for the 100th spectral order of an ESPRESSO observation of GJ699 (black line), sampled with a step of 10 cm s⁻¹ inside the 200 m s⁻¹ search window centered on the ESPRESSO DRS estimate. The parabolic fit is shown as the red line. The red circles represent the RV estimates provided by the Brent method before meeting the convergence criteria. The dashed blue line is the final RV, calculated with Eq. (3), and the dotted green line the ESPRESSO DRS estimate for the given observation.