Which telescope network produced the first image of Sagittarius A*?

The Event Horizon Telescope network produced the first image of Sagittarius A*.

The Event Horizon Telescope, or EHT, is a worldwide network of radio observatories that operates as a planet-sized very-long-baseline interferometer. By combining synchronized observations from widely separated facilities, it achieved the angular resolution needed to study structure on the scale of a black hole’s event horizon.

The collaboration released its first image of Sagittarius A* on May 12, 2022. The underlying observations were made in 2017, using eight radio observatories at six geographic locations. Because Sagittarius A* changes on timescales of minutes, reconstructing a stable image required extensive computational modeling and comparison among independent imaging teams.

The result was not a conventional photograph of the black hole itself. It showed glowing plasma and a bright emission ring surrounding a darker central shadow, produced by the extreme gravity near the event horizon. The EHT had previously released the first image of any black hole—M87*—in 2019; Sagittarius A* was its second black-hole target to be imaged.