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In a meadow on a high mesa southeast of Flagstaff sits the NOI, the Navy Optical Interferometer. From a distance, the instrument resembles irrigation equipment; a series of pipes and what appear to pump houses. But it's actually one of the most sensitive observing devices in the world. Until recently, it was known as the NPOI, or Navy Prototype Optical Interferometer.

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Photo: Mark Duggan

The Navy Optical Interferometer, at first or even second glance, looks like agricultural or irrigation equipment. But its actually one of the most sensitive observing instruments in the world.

From the U.S. Naval Observatory's website:

NPOI is a specialized astronomical telescope called an interferometer. Instead of a single telescope, an array of six mirrors spaced tens of meters apart precisely direct beams of light from a star to a point. Extraordinary image detail can be derived from the resulting data. NPOI can record images of stars and optically separate distant pairs of stars so close together that they appear as a single star in even the largest conventional telescopes. NPOI has the ability to measure the precise relative positions of stars across the sky which the Naval Observatory uses as a reference system for the determination of positions on earth and in space and for monitoring time keeping. Currently operating at about one-fourth of its designed capability, when finished the interferometer will span the distance of over four football field lengths, 430 meters.

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Photo: Mark Duggan

Astronomer Nat White in the control room at the Navy Optical Interferometer.

The NOI sits on land owned by Lowell Observatory. Retired Lowell astronomer Nat White took reporter Mark Duggan on a tour of the NOI, and explained a bit more about its capabilities.

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