Astrometric Positions and Proper Motions of 19 Radio Stars
Abstract
We have used the Very Large Army linked with the Pie Town Very Long Baseline Array antenna to determine astrometric positions of 19 radio stars in the International Celestial Reference Frame (ICRF). The positions of these stars were directly linked to the positions of distant quasars though phase referencing observations. The positions of the ICRF quasars are known to 0.25 mas thus providing an absolute reference at the angular resolution of our radio observations. Average values for the errors in our derived positions for all sources were 13 mas and 16 mas in alpha cos delta and delta respectively with accuracies approaching 1-2 mas for some of the stars observed. Differences between the ICRF positions of the 38 quasars and those measured from our observations showed no systematic offsets with mean values of -0.3 mas in alpha cos delta and - 1.0 mas in delta. Standard deviations of the quasar position differences of 17 mas and 11 mas in alpha COS delta and delta respectively are consistent with the mean position errors determined for the stars. Our measured positions were combined with previous Very Large Array measurements taken from l978-l995 to determine the proper motions of 15 of the stars in our list. With mean errors of ^1.6 mas yr(-1) the accuracies of our proper motions approach those derived from Hipparcos and for a few of the stars in our program are better than the Hipparcos values. Comparing the positions of our radio stars with the Hipparcos catalog we find that the two frames are aligned to within formal errors of approximately 3 mas. This result confirms that the Hipparcos frame is inertial at the expected level.
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 18, 2003
- Accession Number
- ADA412668
Entities
People
- A. L. Fey
- C. De Vegt
- D. A. Boboltz
- K. J. Johnston
- M. J. Claussen
Organizations
- United States Naval Observatory