Evaluation of a possible upgrade of the IAU 2006 precession
Evaluation of a possible upgrade of the IAU 2006 precession
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DOI：
10.1051/0004-6361/201628717
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发表时间：
2017
影响因子：
6.5
通讯作者：
J. Liu;N. Capitaine
中科院分区：
文献类型：
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作者：
J. Liu;N. Capitaine
国际天文学联合会（IAU）在其2006年大会上通过了一个新的岁差模型。自所谓的IAU 2006年岁差发表以来的十多年中，我们注意到太阳系星历和地球物理观测的进展，这些进展可用于完善岁差模型。另一个进展是自2003年以来，甚长基线干涉测量（VLBI）观测的长度增加了30%，用于与理论模型进行比较。目的本文的目的是研究基于地月质心（EMB）运动的新解，对岁差率的新理论贡献，方法通过将新的行星理论VSOP 2013拟合到数值星历DE 422或INPOP 10a上，推导出新的黄道岁差表达式。利用包含J2二次长期变化的更新地球模型，积分动力学岁差方程，得到赤道岁差的解。利用到2015年为止最精确的VLBI观测数据，将新的岁差表达式（本文记为LC解）与IAU 2006模型进行了比较。结果对于黄道岁差，新的解相对于IAU 2006模型在PA和QA的线性项上的变化约为几十微弧秒。由于J2模型的修正，赤道的升级岁差使得数量ω A中的二次项和三次项与IAU 2006有很大的不同。VLBI天极偏移量的统计（1979-2015）和最小二乘拟合不同的经验模型，表明LC岁差与VLBI观测结果稍微一致，结论用最新的理论和观测改进得到的LC岁差的改进，在某些方面显示出了一定的优势，IAU 2006模型。然而，由于黄道岁差的变化可以忽略不计，J2变化的不确定性很大，我们建议保留标准的IAU 2006模型，以供实际使用和连续性的考虑。下一个岁差章动模型应该在ICRF 3和Gai参考框架下采用统一的动力学方法构造，而不使用传统的黄道。
ContextThe International Astronomical Union (IAU) adopted a new precession model at its 2006 General Assembly. After more than ten years since the publication of the so-called IAU 2006 precession, we have noticed progress in solar system ephemerides and geophysical observations, which can be used to refine the precession model. Another progress is the increase by 30% since 2003, of the length of the very long baseline interferometry (VLBI) observations to be compared with the theoretical model.AimsThe aim of this paper is to investigate the possibility of upgrading the IAU 2006 precession model based on new solutions of the Earth-Moon barycenter (EMB) motion, new theoretical contributions to the precession rates, and the revisedJ2long-term variation obtained from the satellite laser ranging (SLR).MethodsThe new precession expressions for the ecliptic are derived by fitting the new analytical planetary theory VSOP2013 to the numerical ephemerides DE422 or INPOP10a. The solution for the precession of the equator was obtained by integrating the dynamical precession equations with the use of an updated Earth model including theJ2quadratic long-term variation. The new precession expressions (denoted LC solution in this paper) are compared with the IAU 2006 model by using the most accurate VLBI observations up to 2015.ResultsFor the precession of the ecliptic, the changes in the new solutions with respect to the IAU 2006 are about several tens of microarcseconds in the linear terms ofPAandQA. The upgraded precession of the equator is such that the quadratic and cubic terms in the quantityψAdiffer significantly from IAU 2006 due to the revisedJ2model. The statistics of the VLBI celestial pole offsets (1979–2015) and least squares fits with different empirical models, show that the LC precession is slightly more consistent with the VLBI observations, but the improvement relative to the IAU 2006 model is not definitely convincing at present.ConclusionsThe upgraded LC precession obtained with the latest theoretical and observational improvements has shown some advantages with respect to the IAU 2006 model. However, due to negligible changes in the precession of the ecliptic and large uncertainties in theJ2variation, we recommend that the standard IAU 2006 model be retained for practical use and continuity reason. The next precession-nutation model should be constructed with a uniform dynamical approach in the framework of ICRF3 andGaiareference frame and without the use of a conventional ecliptic.