The Brown Dwarf Kinematics Project (BDKP. III. Parallaxes for 70 Ultracool Dwarfs
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We report parallax measurements for 70 ultracool dwarfs UCDs including 11 late-M, 32 L, and 27 T dwarfs. In this sample, 14 M and L dwarfs exhibit low surface gravity features, 6 are close binary systems, and 2 are metal-poor subdwarfs. We combined our new measurements with 114 previously published UCD parallaxes and optical mid- IR photometry to examine trends in spectral-typeabsolute magnitude, and color color diagrams. We report new polynomial relations between spectral type and MJHK. Including resolved LT transition binaries in the relations, we find no reason to differentiate between a bright unresolved binary and a faint single source sample across the LT boundary. Isolating early T dwarfs, we find that the brightening of T0 T4 sources is prominent inMJ where there is a 1.2 1.4 mag difference.