Additional contribution to the apparent line-of-sight velocity given by the combination of the special relativistic Doppler effect and gravitational time dilation for the S2 star in the Galactic Center. The relativistic redshift component is maximized around the pericenter (at t ~ 2002 and t ~ 2018), reaching an additional contribution of ~200 km/s (Do et al. 2019; Gravity Collaboration 2018), where the star goes deeper in the gravitational potential well of Sgr A* and is accelerated to its maximum orbital velocity.