Systematic effect of the Galactic aberration on the ICRS realization and the Earth orientation parameters
Systematic effect of the Galactic aberration on the ICRS realization and the Earth orientation parameters
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DOI：
10.1051/0004-6361/201219421
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发表时间：
2012-08
影响因子：
6.5
通讯作者：
J. Liu;N. Capitaine;S. Lambert;Z. Malkin;Zi Zhu
中科院分区：
文献类型：
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作者：
J. Liu;N. Capitaine;S. Lambert;Z. Malkin;Zi Zhu
上下文太阳系质心绕银心运动的曲率引起随时间线性变化的像差效应。它可以被称为“银河系光行差”，也被称为“长期光行差（漂移）”或“自行光行差”。这导致了遥远的河外天体系综的视自行的系统偶极模式，用于定义国际天体参考系（ICRS）。目标。本文的目的是研究银河系光行差对ICRS实现的影响以及对ICRS所涉及的地球定向参数（EOP）的影响。方法.我们首先计算的全球性旋转的天体参考系造成的银河系的光行差效应的星系外天体，实现这个系统的合奏的视自行。然后利用基于CIO的ICRS-to-ITRS坐标转换方法，评估了银河系像差对EOP的影响。数值评估的效果进行了ICRF 1和ICRF 2目录在短时间和长时间间隔。结果我们表明，银河系的畸变的影响强烈依赖于用于实现ICRS的源的分布。根据ICRF 1和ICRF 2星表的源的不同分布，ICRS的视旋转幅度约为每年0.2到1微弧秒（μas yr −1）。我们表明，这种旋转没有围绕指向银河系中心的轴的分量，并在均匀分布的源的情况下具有零振幅。从J2000.0开始，一个世纪后对天球中间极坐标（CIP）的影响在1 ~ 100 μ s之间，而对地球自转角（ERA）的影响在4 ~几十μ s之间。结论.我们表明，银河系的畸变是负责的ICRS轴的方向随时间的变化，因此为确定的EOP，这是指ICRS的系统误差。对ICRS和EOP的影响随着时间的推移而增加，并且在几十年后不可忽略。随着高精度天体测量和VLBI观测时间序列长度的增加，这种影响应予以考虑，特别是在构建ICRS的下一个实现时。应发展对更多射电源的观测，特别是在南半球，以便在ICRF中更均匀地分布定义源，以尽量减少这种影响。
Context. The curvature of the motion of the solar system barycenter around the Galactic center induces an aberration effect varying linearly with time. It can be called the “Galactic aberration” and is also known as the “secular aberration (drift)” or “aberration in proper motions”. This results in a systematic dipole pattern of the apparent proper motions of an ensemble of distant extragalactic objects, which are used to define the International Celestial Reference System (ICRS). Aims. The purpose of this paper is to investigate the effect of the Galactic aberration on the ICRS realization and on the Earth orientation parameters (EOP), which refer to the ICRS. Methods. We first computed the global rotation of the celestial reference system resulting from the Galactic aberration effect on the apparent proper motions of the ensemble of extragalactic objects that realize this system. Then we evaluated the influence of the Galactic aberration on the EOP using CIO based ICRS-to-ITRS coordinate transformation. Numerical evaluations of the effect were performed with the ICRF1 and ICRF2 catalogs over short and long time intervals. Results. We show that the effect of the Galactic aberration strongly depends on the distribution of the sources that are used to realize the ICRS. According to different distributions of sources (of the ICRF1 and ICRF2 catalogs) the amplitude of the apparent rotation of the ICRS is included between about 0.2 and 1 microarcsecond per year (μas yr −1 ). We show that this rotation has no component around the axis pointing to the Galactic center and has an zero amplitude in the case of uniform distribution of sources. The effect on the coordinates of the Celestial intermediate pole (CIP) is included between about 1 to 100 μas after one century from J2000.0, while the effects on the Earth rotation angle (ERA) are from 4 to several tens of μas after one century. Conclusions. We demonstrate that the Galactic aberration is responsible for a variation with time of the orientation of the ICRS axes and consequently for systematic errors on the determination of the EOP, which refer to the ICRS. The effect on the ICRS and EOP increases with time and is not negligible after several tens of years. With high-accuracy astrometry and the increasing length of the available VLBI observation time series, this effect should be considered, particularly in constructing the next realization of the ICRS. Observations of more radio sources, especially in the southern hemisphere should be developed to more homogeneously distribute defining sources in the ICRF to minimize that effect.