http://www.newsweek.com/event-horizon-telescope-groundbreaking-announcement-1382918

In 2017, scientists set out on a mission to take the very first picture of a black hole's event horizon. Over 10 days, the team observed Sagittarius A*—the black hole that sits at the center of the Milky Way. They linked up telescopes around the globe virtually, and by doing so created one huge, Earth-sized telescope.

Over the observation period, the Event Horizon Telescope team collected a petabyte of data. This was then distributed to two research institutions—MIT Haystack, in the U.S., and the Max Planck Institute for Radio Astronomy, Germany. The data was then processed by supercomputers.