The Event Horizon Telescope makes use of a technique called Very Long Baseline Interferometry (VLBI) that requires several telescopes observing the same object from different locations to create highly detailed images of very, very small sections of the sky. The farther apart the telescopes are located, the greater the detail they can achieve. The Event Horizon Telescope will link eight radio telescopes around the world, including the Atacama Large Millimeter/submillimeter Array in Chile, the Caltech Submillimeter Observatory in Hawaii, the Large Millimeter Telescope Alfonso Serrano in Mexico, the South Pole Telescope in Antarctica, and other facilities in France and Spain to utilize the longest baselines possible. By creating a truly Earth-sized telescope, the project should be capable of imaging the space around a black hole in exquisite detail.
This will allow astronomers to study not only the structure of the disk around the black hole, but also to test general relativity, get a better look at how the black hole actually feeds on material, and maybe even determine how the outflows and jets that are so common among black holes are actually created.
The giant telescope came online April 5 and will observe for about a week and a half, gathering data until April 14. In addition to imaging our relatively quiescent Sgr A*, it will also look at the more active supermassive black hole residing in Messier 87, a huge elliptical galaxy in the nearby Virgo Cluster. The amount of information obtained will be so immense that it’s too large to transfer digitally — it will be stored physically and taken to the Max Planck Institute in Germany, and the Haystack Observatory in Massachusetts for processing.
http://www.astronomy.com/news/2017/04/first-image-of-a-black-hole