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From a press release of the Max Planck Institute for Radio Astronomy, April 21, 2015:

Joint observations by the Atacama Pathfinder Experiment (APEX) telescope in Chile and Antarctica’s largest astronomical telescope come closer to making detailed images of the supermassive black hole in the centre of the Milky Way, up to its very edge, the “event horizon”. These successful observations were conducted within the framework of the Event Horizon Telescope – a virtual telescope as big as planet Earth.

Event Horizon Telescope

Credit: © Dan Marrone/University of Arizona

The South Pole Telescope (SPT) and APEX joined together in a ‘Very Long Baseline Interferometry’ experiment for the first time in January 2015. The two telescopes together observed two sources — the black hole at the centre of the Milky Way galaxy, Sagittarius A*, and the black hole at the centre of the nearby galaxy Centaurus A — and combined their signals to synthesize a telescope 7,000 kilometres across. With this success, the SPT joins the Event Horizon Telescope array, which connects APEX, the Large Millimeter Telescope in Mexico, the Submillimeter Telescope in Arizona, the Combined Array for Research in Millimeter-wave Astronomy in California, the Submillimeter Array and James Clerk Maxwell Telescope in Hawaii, and the Institute for Radio Astronomy Millimetrique (IRAM) telescopes in Spain and France.

Even though the Milky Way’s black hole is 4 million times more massive than the Sun, it is tiny to the eyes of astronomers. Smaller than Mercury’s orbit around the Sun, yet almost 26,000 light years away, studying its event horizon in detail is equivalent to standing in New York and reading the date on a cent in Germany.

With its unprecedented resolution, more than 1,000 times better than the Hubble Telescope, the EHT will see swirling gas on its final plunge over the event horizon, never to regain contact with the rest of the universe. If the theory of general relativity is correct, the black hole itself will be invisible because not even light can escape its immense gravity. However, it might still be seen as a silhouette against the background.

Links: MPIfR press release; EHT home.


Read an up-to-date survey of various new telescopes and systems, by Dennis Overbye of The New York Times (July 21, 2014).

Overbye discusses the funding, construction, and schedule for the E-ELT, the Giant Magellan Telescope, and the Thirty-Meter Telescope, as well as the Large Synoptic Survey Telescope. For space telescopes, he discusses the new Hubble-class satellites given to NASA by the National Reconnaissance Office, to be used in Wfirst-AFTA (he quotes David Spergel of Princeton as saying that “The good thing about Wfirst-AFTA is that there is no way that we will keep that name.” He winds up by discussing the case of the James Webb Space Telescope, due for launch in 2018, now on its revised budget and schedule, following its role as “the telescope that ate astronomy.”

Credit: Ball Aerospace

Credit: Ball Aerospace

Links: the NY Times article by Dennis Overbye.