Deep images of the Galactic center with GRAVITY

Stellar orbits at the Galactic Center provide a very clean probe of gravitational potential supermassive black hole. They can be studied with unique precision, beyond confusion limit single telescope, near-infrared interferometer GRAVITY. Imaging is essential to search field for faint, unknown stars on short which potentially could constrain hole spin. Furthermore, it provides starting point astrometric fitting derive highly accurate stellar positions. Here, we present G R , new imaging tool specifically designed observations The algorithm based Bayesian interpretation problem, formulated in framework information theory and building upon existing works radio-interferometric imaging. Its application GRAVITY from 2021 yields deepest images date scales few milliarcseconds. reveal complicated source structure within central 100 mas around Sgr A*, where detected S29 S55 confirm S62 its trajectory, slowly approaching A*. were able detect S38, S42, S60, S63 series exposures offset fiber We an update all aforementioned stars. In addition these known sources, also faint star moving west high angular velocity. cannot find any coincidence and, thus, refer as S300. From flux ratio S29, estimate K -band magnitude m (S300) ? 19.0 ? 19.3. Images obtained CLEAN detection. To assess sensitivity our images, note that damping reduces apparent S300 effect increases throughout year moves away center. performed injection tests. Under favorable circumstances, sources well below 20 recovered, while 19.7 considered more universal good data set.