The first image of a black hole was released in 2019 by which international telescope collaboration?

The international telescope collaboration that released the first image of a black hole in 2019 was the Event Horizon Telescope.

The Event Horizon Telescope, or EHT, is not one conventional telescope. It is a worldwide network of radio observatories that work together using very-long-baseline interferometry. By combining observations from facilities separated by thousands of kilometres, astronomers created an Earth-sized virtual telescope with enough resolving power to study the region around a black hole.

On April 10, 2019, the EHT Collaboration unveiled an image of the supermassive black hole at the centre of the galaxy Messier 87, about 55 million light-years from Earth. The famous orange-red ring is hot glowing gas surrounding a dark central shadow created by the black hole’s extreme gravity. The image tested predictions of Albert Einstein’s general theory of relativity under extraordinarily strong gravitational conditions.

This was not a photograph of the black hole’s surface, because no light escapes from inside its event horizon. The image shows the black hole’s shadow and surrounding emission. The EHT later produced the first image of Sagittarius A*, the Milky Way’s central black hole, in 2022.