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R. A. Gaume, K. J. Johnston (U.S. Naval Observatory), AMEX Program Team
The Astrometric Mapping Explorer (AMEX) is an astrometric space mission proposed to NASA in the Small Explorers (SMEX) program. The main goal of AMEX is to obtain astrometry and spectro-photometry of the 40 million brightest stars in the sky. AMEX is a joint project between the U.S. Naval Observatory (USNO), the German space agency (DLR), the Jet Propulsion Laboratory (JPL), and Astrium (Germany).
AMEX will rotate every 2 hours with a 56 day precession period. The AMEX instrument has a compound mirror so that two fields of view are imaged onto the same focal plane. Each field of view of 0.6 degrees is imaged by 2 rows of 4 astrometric CCDs and 2 rows of 4 spectroscopic CCDs. After the three year mission, the astrometric accuracy will be about 150 (2000) microarcseconds at V=9 (V=15). Photometry is derived from the astrometric CCDs in the astrometric band (400 to 1000 nm), and from a low-resolution spectroscopic instrument.
AMEX data will significantly impact a number of astronomy sub-disciplines. AMEX results will include the following:
A comprehensive characterization of stars in the Solar neighborhood (< 10% parallax errors within 1 kpc) including, kinematics, proper motions and distances.
Astrometric detection of several thousand giant planets (M < 10 MJup and P < 6 yr) around Sun-like stars within 120 pc, with a definitive determination of the frequency of brown dwarf companions in the mass range 10 to 80 MJup (which includes the brown dwarf desert) and periods less than six years, together with photometric detection of hundreds of transiting hot Jupiters around parent stars brighter than R=11.
A determination, for millions of stars brighter than R=13.5, of numerous astrophysical parameters, including surface gravity, effective temperature, and metallicity, as well as the values of interstellar extinction toward these stars.
Calibration of the absolute luminosities of standard candles that define the distance scale to galaxies.
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Bulletin of the American Astronomical Society, 35#5
© 2003. The American Astronomical Soceity.