The Allen Telescope Array (ATA), formerly known as the One Hectare Telescope (1hT), is a radio telescope array dedicated to astronomical observations and a simultaneous search for extraterrestrial intelligence (SETI). The array is situated at the Hat Creek Radio Observatory in Shasta County, 290 miles (470 km) northeast of San Francisco, California.
The Allen Telescope Array (ATA-42), October 11, 2007.
The ATA Offset Gregorian Design
Astronomical interferometer
An astronomical interferometer or telescope array is a set of separate telescopes, mirror segments, or radio telescope antennas that work together as a single telescope to provide higher resolution images of astronomical objects such as stars, nebulas and galaxies by means of interferometry. The advantage of this technique is that it can theoretically produce images with the angular resolution of a huge telescope with an aperture equal to the separation, called baseline, between the component telescopes. The main drawback is that it does not collect as much light as the complete instrument's mirror. Thus it is mainly useful for fine resolution of more luminous astronomical objects, such as close binary stars. Another drawback is that the maximum angular size of a detectable emission source is limited by the minimum gap between detectors in the collector array.
ESO's VLT interferometer took the first detailed image of a disc around a young star.
A 20-foot Michelson interferometer mounted on the frame of the 100-inch Hooker Telescope, 1920.
Aerial view of the ESO/NAOJ/NRAO ALMA construction site.
The Navy Precision Optical Interferometer (NPOI), a 437 ma baselined optical/near-infrared, 6-beam Michelson Interferometer at 2163 m elevation on Anderson Mesa in Northern Arizona, USA. Four additional 1.8-meter telescopes are being installed starting from 2013.