Multiple telescopes, including Chandra, observed the Milky Way’s giant black hole simultaneously with the Event Horizon Telescope (EHT). This combined effort gave insight into what is happening farther out than the field-of-view of the EHT.
Click here for original story, Sagittarius A*: NASA Telescopes Support Event Horizon Telescope in Studying Milky Way’s Black Hole
Source: NASA Goddard Center