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NEAT: A Microarcsec Astrometric TelescopeNEAT, Nearby Exo-Earth Astrometric Telescope is a medium-small telescope (is) approximately 1m in diameter that is designed to make ultra precise (is) less than 1 uas (microarcsec) astrometric measurements of nearby stars in a (is) approximately 1hr observation. Four major error sources prevent normal space telescopes from obtaining accuracies close to 1 uas. Even with a small 1m telescope, photon noise is usually not a problem for the bright nearby target stars. But in general, the reference stars are much fainter. Typically a field of view of (is) approximately 0.5 deg dia is needed to obtain enough bright reference stars. The NEAT concept uses a very simple but unusual design to avoid optically induced astrometric errors. The third source of error is the accuracy and stability of the focal plane. A 1uas error over a (is) approximately 2000 arcsec field of view implies the focal plane is accurate or at least stable to 5 parts in 10(exp 10) over the lifetime of the mission ( (is) approximately 5yrs). The 4th class of error has to do with our knowledge of the PSF and how that PSF is sampled by an imperfect detector. A Nyquist sampled focal plane would have (is) greater than 2 pixels per lambda/D, and centroiding to 1uas means centroiding to 10-5 pixels. This paper describes the mission concept, and an overview of the technology needed to perform 1uas astrometry with a small telescope, and how we overcome problems 1 and 2. A companion paper will describe the technical progress we've made in solving problems 3 and 4.
Document ID
20150006808
Acquisition Source
Jet Propulsion Laboratory
Document Type
Conference Paper
External Source(s)
Authors
Shao, M.
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Nemati, B.
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Zhai, C.
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Goullioud, R.
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Date Acquired
April 27, 2015
Publication Date
August 17, 2011
Subject Category
Astronomy
Distribution Limits
Public
Copyright
Other
Keywords
Earth like planets
exo-planets

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