2 research outputs found
VLA+PT Astrometry of 46 Radio Stars
We have used the Very Large Array (VLA), linked with the Pie Town Very Long
Baseline Array antenna, to determine astrometric positions of 46 radio stars in
the International Celestial Reference Frame (ICRF). Positions were obtained in
the ICRF directly through phase referencing of the stars to nearby ICRF quasars
whose positions are accurate at the 0.25 mas level. Radio star positions are
estimated to be accurate at the 10 mas level, with position errors approaching
a few milli-arcseconds for some of the stars observed. Our measured positions
were combined with previous measurements taken from as early as 1978 to obtain
proper motion estimates for all 46 stars with average uncertainties of ~1.7
mas/yr. We compared our radio star positions and proper motions with the
Hipparcos Catalogue data, and find consistency in the reference frames produced
by each data set on the 1-sigma level, with errors of ~2.7 mas per axis for the
reference frame orientation angles at our mean epoch of 2003.78. No significant
spin is found between our radio data frame and the Hipparcos Celestial
Reference Frame (HCRF) with largest rotation rates of +0.55 and -0.41 mas/yr
around the x and z axes, respectively, with 1-sigma errors of 0.36 mas/yr.
Thus, our results are consistent with a non-rotating Hipparcos frame with
respect to the ICRF.Comment: 29 pages, 8 figures, accepted for publication in the Astronomical
Journa