Name/Affiliation: Frederick Vrba (U.S. Naval Observatory)
Improved Parallaxes and Near-Infrared Photometry of L- and T- Dwarfs From The US Naval Observatory Infrared Astrometry Program
In 2004 USNO published one of the first comprehensive studies of high-quality parallaxes and proper motions of 40 L- and T-dwarfs based on near-infrared observations obtained with ASTROCAM at the Flagstaff Station's 1.55-m telescope. Since that time additional observations of the original 40 objects along with another 19 objects have greatly improved the astrometric results. In this paper we present the parallax results, along with new near-infrared photometry, in the form of spectral type versus absolute magnitude and color-color diagrams.