Eight radio telescopes were used to image a black hole. They were ALMA, APEX, the IRAM 30-meter telescope, the James Clerk Maxwell Telescope, the Large Millimeter Telescope Alfonso Serrano, the Submillimeter Array, the Submillimeter Telescope, and the South Pole Telescope.
Three more radio telescopes will be added to the Event Horizon Telescope project (EHT) over the next two years. This will improve the imaging resolution and the sensitivity of the array.
A fourth radio telescope will also be added to reach a 12-telescope global array.
These radio telescopes are the Greenland Telescope, IRAM NOEMA Observatory and the Kitt Peak National Observatory (KPNO).
The Greenland Telescope project represents a creative way to conduct state-of-the-art science. The 12-meter radio antenna was originally built as a prototype for the Atacama Large Millimeter/Submillimeter Array (ALMA) project, currently in operations in Chile.
By repurposing this telescope to Greenland, astronomers can take advantage of the near-ideal conditions of the Arctic to study the Universe at specific radio frequencies.
IRAM NOEMA (NOrthern Extended Millimeter Array) Observatory
NOEMA, the successor to the Plateau de Bure observatory, is the most powerful millimeter radiotelescope of the Northern Hemisphere and one of the most advanced facilities existing today for radio astronomy:
Located in the French Alps on the wide and isolated Plateau de Bure at an elevation of 2550 meters, the telescope currently consists of ten antennas, each 15 meters in diameter. Each antenna is equipped with state-of-the-art high-sensitivity receivers. Two tracks, extending on a north-south and east-west axis, enable the antennas to be moved up to a maximum separation of 760 meters.
NOEMA will double the number of antennas of its predecessor from six to twelve. The first of the six new NOEMA antennas was inaugurated end of September 2014. Since then, two other antennas have entered scientific operation. During the next years, construction of the array will continue and three other antennas will follow, approximately one per year until 2020.
Once finished, NOEMA will be the most advanced facility for millimeter radio astronomy in the Northern Hemisphere. Its spatial resolution will be four times higher and its sensitivity ten times better than those of its predecessor.
Kitt Peak National Observatory
Kitt Peak operates 22 optical telescopes and two radio telescopes.
SOURCE – EHT project, Kitt Peak National Observatory, IRAM NOEMA observatory, Greenland Telescope project
Written By Brian Wang, Nextbigfuture.com