Test of source selection for constructing a more stable and uniform celestial reference frame
Test of source selection for constructing a more stable and uniform celestial reference frame
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DOI：
10.1093/mnras/stw3156
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发表时间：
2016-12
影响因子：
4.8
通讯作者：
N. Liu;J. Liu;Z. Zhu
中科院分区：
文献类型：
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作者：
N. Liu;J. Liu;Z. Zhu
我们的目标是通过调查1979年至2016年期间VLBI观测到的射电源的坐标时间序列，评估从ICRF 2目录开始改进ICRS实现的可能性。选择具有长观测历史的源作为候选源，并执行具有特殊处理的权重的最小二乘拟合以导出源坐标的线性漂移。然后基于归一化的线性漂移（i）在整个天空上和（ii）在由赤纬划分的四个同相区域中对源进行排序。对参考系的轴向稳定性和由选定源定义的天空分布进行了评估，并以此作为最终源列表的判据。与我们改进的源选择方案，两组源的建议，并认为适合定义一个更稳定和均匀的天球参考系相比，目前的ICRF 2。最后列表中的源的数量分别为323和294，并且由源的视运动导出的轴的全球旋转比ICRF 2好大约两倍。
We aim to evaluate the possibility of improving the ICRS realization starting from the ICRF2 catalogue by investigating the coordinate time series of radio sources observed by VLBI between 1979 and 2016. Sources with long observational history are selected as the candidates and the least squares fits with special handling of the weights are performed to derive the linear drifts of the source coordinates. Then the sources are sorted based on the normalized linear drift (i) over the whole sky and (ii) in four homolographic areas divided by declinations. The axial stability of the reference system and sky distribution defined by the selected sources are evaluated, which are acted as the criterion for the final source lists. With our improved source selection scheme, two groups of sources are proposed and considered suitable for defining a more stable and homogeneous celestial reference system compared to the current ICRF2. The number of sources in the final lists are 323 and 294, respectively, and the global rotation of the axes derived from apparent motion of the sources are about two times better than the ICRF2.