文章基本信息

标题：Very Long Baseline Array Astrometry of Cassini: The Final Epochs and an Improved Orbit of Saturn
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作者：Dayton L.Jones ; William M.Folkner ; Robert A.Jacobson 等
期刊名称：The Astronomical journal
印刷版ISSN：0004-6256
电子版ISSN：1538-3881
出版年度：2020
卷号：159
期号：2
页码：1024-1031
DOI：10.3847/1538-3881/ab5f5d
语种：English
出版社：American Institute of Physics
摘要：We report results from multi-epoch radio astrometry of the Cassini spacecraft with the Very Long Baseline Array (VLBA).These observations are part of a program to determine a series of accurate positions for the Saturn system barycenter in the inertial International Celestial Reference Frame (ICRF) and to use these position measurements to improve our knowledge of Saturn's orbit in the planetary ephemeris.Our VLBA observations cover the full duration of the orbital phase of the Cassini mission, from Saturn orbit insertion in 2004 to the end of mission in 2017.This period covers more than one-third of Saturn's orbital period, allowing us to obtain good orbit constraints for Saturn, particularly on the inclination and ascending node longitude.During the early years of Cassini's orbital mission our VLBA data dominated the determination of orbit orientation, while later in the mission range measurements become more significant.The orientation of Saturn's orbit is now known to approximately 0.25 milli-arcseconds (1.25 nrad), an order of magnitude improvement since the start of Cassini observations.Continuing improvements in the ICRF position accuracy for our phase reference sources, and possible improvements in the final orbit solutions for Cassini, may lead to a still better Saturn orbit over the coming years.
关键词：Radio astrometry;Ephemerides;Saturn