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Paper: Progress in Parallaxes at USNO
Volume: 338, Astrometry in the Age of the Next Generation of Large Telescopes
Page: 122
Authors: Harris, H.C.; Canzian, B.; Dahn, C.C.; Guetter, H.H.; Henden, A.A.; Levine, S.E.; Luginbuhl, C.B.; Monet, A.K.B.; Monet, D.G.; Munn, J.A.; Pier, J.R.; Stone, R.C.; Tilleman, T.; Vrba, F.J.; Walker, R.L.
Abstract: The accuracy of trigonometric parallaxes from the U.S. Naval Observatory (USNO) has continued to improve. An optical CCD camera is used regularly on the 61-inch telescope. It produces parallaxes with typical errors of ±0.5 mas, and can reach ±0.3 mas with some effort. The program provides distances, absolute magnitudes, and tangential velocities accurate to a few percent for many white dwarfs and low-luminosity red and brown dwarfs. Other classes of special interest being observed are planetary nebulae, cataclysmic variables, dwarf novae, and dwarf carbon stars. Some stars show residual perturbations from a close companion, and the astrometric orbital solutions indicate a brown dwarf or (in a few cases) a possible planetary-mass companion. In addition, a near-IR InSb camera is used for parallaxes of very red L and T brown dwarfs. We discuss the relationship of USNO and other programs, and the prospects for further progress.
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