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G.R. Knapp (Princeton), X. Fan (Arizona), D.J. Schlegel (LBNL), D.P. Finkbeiner, N. Padmanabhan, M.A. Strauss, J.E. Gunn, R.H. Lupton (Princeton), Z. Ivezic (U.Washington)
The high astrometric accuracies of the Sloan Digital Sky Survey and the Two-Micron All Sky Survey (better than 200 mas for both surveys) allow proper motions to be measured from SDSS repeat observations and from 2MASS vs SDSS observations to typically 40 mas/year or better. This can be applied to derive proper motions for nearby brown dwarfs, which are too red and faint to be well represented in the recent massive proper motion surveys derived from photographic plate material. While this accuracy is low compared to the high quality measurements by, e.g. Vrba et al. 2004, AJ 127, 2948, it is sufficient to measure proper motions for about 200 spectroscopically confirmed L and T dwarfs, allowing a statistical study of the relative ages of these objects and confirming the larger average ages of the T dwarfs.
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Bulletin of the American Astronomical Society, 37 #4
© 2005. The American Astronomical Soceity.