A global collaboration for an Earth-sized telescope

The EHT is an international collaboration capturing images of black holes using a virtual Earth-sized telescope.

The EHT array is going after what’s known as the event horizon. This is the invisible boundary thought to surround all black holes, a point beyond which light cannot return.

The regions around supermassive black holes experience the most extreme conditions that we know of in the universe today.

The telescopes of the EHT array observe in the so-called VLBI mode (Very Long Baseline Interferometry), a groundbreaking technique, that links the most sensitive radio telescopes on 4 continents to take the first-ever image of a black hole.

To observe these black holes, astronomers need to reach a sensitivity and spatial resolution that would be capable of reading the text of a newspaper in New York by a reader situated in Europe. To achieve this level of resolution, EHT synchronises facilities around the world and exploits the rotation of our planet to form one huge telescope with a theoretical aperture equal to the diameter of Earth itself.

European observatories are at the forefront of this global adventure.

The IRAM 30-meter telescope and the NOEMA observatory, have pioneered (VLBI)-millimeter-network observations of our galactic center and its near vicinity in the 1990s. Until today, IRAM’s facilities are the only telescopes on European ground that match the specific requirements for this global project.

In late 2018, NOEMA joined the EHT array. With its twelve high-precision antennas, NOEMA gives the global EHT telescope network unprecedented spatial resolution and sensitivity.

As such, NOEMA serves as a new and crucial ‘anchor station’ allowing the use of less sensitive stations. Due to its location in France, NOEMA also extends the east-west baselines that link the different observing stations, up to Hawaii. Longer baselines mean an enlarged virtual telescope with increasing angular resolution. In other words, EHT scientists will be able to ‘zoom’ even more into cosmic details.