A geometric distance measurement to the Galactic center black hole with 0.3% uncertainty

We present a 0.16% precise and 0.27% accurate determination of R 0 , the distance to the Galactic center. Our measurement uses the star S2 on its 16-year orbit around the massive black hole Sgr A* that we followed astrometrically and spectroscopically for 27 years. Since 2017, we added near-infrared interferometry with the VLTI beam combiner GRAVITY, yielding a direct measurement of the separation vector between S2 and Sgr A* with an accuracy as good as 20 μ as in the best cases. S2 passed the pericenter of its highly eccentric orbit in May 2018, and we followed the passage with dense sampling throughout the year. Together with our spectroscopy, in the best cases with an error of 7 km s −1 , this yields a…

• AV
  Alexander von Humboldt-Stiftung
• DF
  Deutsche Forschungsgemeinschaft
• BF
  Bundesministerium für Bildung und Forschung
• M
  Max-Planck-Gesellschaft
• CN
  Centre National de la Recherche Scientifique
• OD
  Observatoire de Paris, Université de Recherche Paris Sciences et Lettres
• FP
  Fundação para a Ciência e a Tecnologia

  Award: UID/FIS/00099/2013