Status of the USNO Infrared Astrometry Program (Poster abstract)

Volume 40 number 1 (2012)

Frederick John Vrba

U.S. Naval Observatory, Flagstaff Station, 10391 West Naval Observatory Road, Flagstaff, AZ 86001; address correspondence to J. Vrba at fjv@nofs.navy.mail

Jeffrey A. Munn

U.S. Naval Observatory, Flagstaff Station, 10391 West Naval Observatory Road, Flagstaff, AZ 86001; address correspondence to J. Vrba at fjv@nofs.navy.mail

Christian B. Luginbuhl

U.S. Naval Observatory, Flagstaff Station, 10391 West Naval Observatory Road, Flagstaff, AZ 86001; address correspondence to J. Vrba at fjv@nofs.navy.mail

T. M. Tilleman

U.S. Naval Observatory, Flagstaff Station, 10391 West Naval Observatory Road, Flagstaff, AZ 86001; address correspondence to J. Vrba at fjv@nofs.navy.mail

Arne A. Henden

AAVSO Headquarters, 49 Bay State Road, Cambridge, MA 02138; arne@aavso.org

Harry H. Guetter

U.S. Naval Observatory, Flagstaff Station, 10391 West Naval Observatory Road, Flagstaff, AZ 86001; guetter@commspeed.net

Abstract

(Abstract only) The USNO Infrared astrometry program has been in a suspended state since a June 2006 cryogenic accident with our imaging camera. We describe the current status of bringing the program back to full operation. We expect to re-start an expanded astrometric program in the near future and present our initial list of targets. This will also provide an opportunity for the community to suggest potential cool, low-mass targets which are in need of high quality parallaxes and proper motions. We earlier published preliminary astrometric results for 40 L and T dwarf fields based on the first two years of observations (Vrba et al., Astron. J., 127, 2948 (2004)). Those initial objects plus an additional nineteen fields added later comprise a total of one M dwarf, twenty-eight L dwarfs, and thirty-nine T dwarfs, including objects in binary systems. Final parallaxes and proper motions for these objects will be published later this year. The additional approximately four years of observations for the original forty objects improve the mean parallax errors orginially reported from 4.31 mas to 1.73 mas, with the best at 0.64 mas, and the mean proper motion errors from 6.56 mas/yr to 1.09 mas/yr.