this location, so that the light from outside the field of view does not reach the secondary mirror. This is a major advantage for solar telescopes, where a field stop (Gregorian stop) can reduce the amount of heat reaching the secondary mirror and subsequent optical components. The Solar Optical Telescope on the Hinode satellite is one example of this design. For amateur telescope makers the Gregorian can be less difficult to fabricate than a Cassegrain because the concave secondary is Foucault-testable like the primary, which is not the case with the Cassegrain's convex secondary. Gallery Examples The MeerKAT, the Green Bank Telescope, the Arecibo Observatory, and the Allen Telescope Array are all radio telescopes employing off-axis Gregorian optics. The Vatican Advanced Technology Telescope, the Magellan telescopes, and the Large Binocular Telescope use Gregorian optics. The Giant Magellan Telescope will also use Gregorian optics. The NSF's Daniel K. Inouye Solar Telescope See also List of telescope types Giant Magellan Telescope Gregor telescope at the Teide Observatory. James Gregory is the inventor of the Gregorian telescope. James Gregory Telescope at the university of St. Andrews. Large Binocular Telescope James Short (mathematician) References External links Gregorian reflecting telescope, Who was James Gregory, National Museums Scotland. Kenyon College The Encyclopedia of Astrobiology, Astronomy, and Spaceflight Telescope types Scottish inventions