The impact of gravitational lensing in the reconstruction of stellar orbits around Sgr A*

Abstract After the amazing discoveries by GRAVITY collaboration in last few years on star S2 orbiting black hole Sgr A* center of Milky Way, we present a detailed investigation impact gravitational lensing reconstruction stellar orbits around this massive hole. We evaluate astrometric effects stars S2, S38 and S55 how these systematically affect derived orbital parameters. The effect is below current uncertainties, but not negligible. With addition more observations stars, it will be possible to let shift emerge from statistical noise finally detected. By repeating analysis smaller semimajor axis various inclinations i, are able quantify broader range As expected, for axes nearly edge-on increase about an order magnitude.