The black hole at the heart of our galaxy

On 12 May at a press conference hosted at NSF, the Event Horizon Telescope (EHT) Collaboration revealed the first image of the black hole at the center of our Milky Way galaxy. It is known as Sgr A* or Sagittarius A*. The observations actually occurred in April 2017, while the first black hole photograph, that of Messier 87 (M87*), was created from observations in April 2019 and released the same month.

Because Sgr A* is much closer than M87*, it appears to be approximately the same size. However, M87* is 1500 times more massive and 2000 times more distant.

The telescopes involved in this project included the Atacama Large Millimeter/submillimeter Array (ALMA), the Atacama Pathfinder Experiment (APEX), the IRAM 30-meter Telescope, the James Clerk Maxwell Telescope (JCMT), the Large Millimeter Telescope Alfonso Serrano (LMT), the Submillimeter Array (SMA), the University of Arizona Submillimeter Telescope (SMT), and the South Pole Telescope (SPT). Since then, other instruments including the Greenland Telescope (GLT) at Thule have been added to the EHT array. There are plans to eventually move the GLT to Summit Camp.

Information sources: the main source is this 12 May 2022 NSF press release, which links to this page that provides more information as well as a link to the high resolution image. Other references include this May 2022 open source paper from The Astrophysical Journal Letters titled "Focus on First Sgr A* Results from the Event Horizon Telescope", and this 12 May New York Times article "The Milky Way's Black Hole Comes to Light."