VLBI Astrometry of radio stars to link radio and optical celestial reference frames. I. HD 199178 & AR Lacertae
Journal article, 2023
To accurately link the radio and optical Celestial Reference Frames (CRFs) at optical bright end, i.e. with GaiaG-band magnitude ≾13, increasing number and improving sky distribution of radio stars with accurate astrometric parameters from both Very Long Baseline Interferometry (VLBI) and Gaia measurements are mandatory. We selected two radio stars HD 199178 and AR Lacertae as the target for a pilot program for the frame link, using the Very Long Baseline Array at 15 GHz at six epochs spanning about 1 yr, to measure their astrometric parameters. The measured parallax of HD 199178 is 8.949 ± 0.059 mas and the proper motion is μαcos δ = 26.393 ± 0.093 and μδ = −0.950 ± 0.083 mas yr−1, while the parallax of AR Lac is 23.459 ± 0.094 mas and the proper motion is μαcos δ = −51.906 ± 0.138 and μδ = 46.732 ± 0.131 mas yr−1. Our VLBI measured astrometric parameters have accuracies about 4–5 times better than the corresponding historic VLBI measurements and comparable accuracies with those from Gaia, validating the feasibility of frame link using radio stars. With the updated astrometric parameters for these two stars, there is a ∼25 per cent reduction of the uncertainties on the Y-axis for both orientation and spin parameters.
parallaxes
proper motions
radio continuum: stars
astrometry
reference systems
Author
Wen Chen
Yunnan University
Chinese Academy of Sciences
Yunnan Observatories
Chalmers, Space, Earth and Environment, Onsala Space Observatory
Bo Zhang
Shanghai Astronomical Observatory
Jingdong Zhang
Shanghai Astronomical Observatory
Chinese Academy of Sciences
Jun Yang
Chalmers, Space, Earth and Environment, Onsala Space Observatory
Shuangjing Xu
Korea Astronomy and Space Science Institute
Shanghai Astronomical Observatory
Yan Sun
Shanghai Astronomical Observatory
Xiaofeng Mai
Shanghai Astronomical Observatory
Chinese Academy of Sciences
Fengchun Shu
Shanghai Astronomical Observatory
M. Wang
Yunnan Observatories
Chinese Academy of Sciences
Yunnan University
Monthly Notices of the Royal Astronomical Society
0035-8711 (ISSN) 1365-2966 (eISSN)
Vol. 524 4 5357-5367Subject Categories
Astronomy, Astrophysics and Cosmology
Atom and Molecular Physics and Optics
DOI
10.1093/mnras/stad1214