Sagittarius A*
Event Horizon Telescope reveals the first image of Sagittarius A*
View full image ↗ How was this image made?
The creative brief sent to the image model. These are instructions, not a record of what actually happened.
Original prompt & settings (JSON) ↗The target changed appearance minute to minute — the collaboration likened it to photographing a puppy chasing its tail. The published ring is an average of thousands of reconstructions.
12 May 2022: the ring goes public
At coordinated press conferences on 12 May 2022, the Event Horizon Telescope Collaboration unveiled its first image of Sagittarius A*, the compact object at the center of the Milky Way — about 27,000 light-years away and roughly four million solar masses.
The picture was reconstructed from radio observations made over several nights in April 2017 by eight observatories in Chile, Mexico, Spain, Arizona, Hawaii and Antarctica, linked through very-long-baseline interferometry.
An average, not an exposure
Sagittarius A* changed on minute-scale timescales while it was being observed, so the released image is an average of thousands of reconstructions that all fit the data rather than a single camera exposure.
It is not an optical photograph and it does not show the black hole. The bright ring is glowing gas and gravitationally bent radio emission around a dark central shadow, measured at 51.8 ± 2.3 microarcseconds across. The orange is representational; the observing wavelength was about 1.3 millimetres.
Five years of analysis, then the observing data
The collaboration described five years of correlation, calibration, simulation and image reconstruction between the 2017 observations and this release, drawing on more than 300 researchers at 80 institutions.
The result appeared as a six-paper special issue of The Astrophysical Journal Letters, alongside a public release of the April 2017 observing data. It was the first image of Sagittarius A*, not the first image of a black hole — EHT had revealed M87* in 2019.
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Researched 23 Aug 2026 6 sources 2 audit passes
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Checked against
- EHT: Astronomers Reveal First Image of the Black Hole at the Heart of Our Galaxy
- EHT Collaboration, First Sagittarius A* Results I: The Shadow
- The Astrophysical Journal Letters: First Sagittarius A* Results I
- EHT: Public Data Release of the 2017 Observations
- EHT Status Update, 15 December 2017
- U.S. National Science Foundation: Image of Sagittarius A*