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arXiv 1409.0504astro-ph.IM
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银河系自行光行差对天体参考系的影响

On the implications of the Galactic aberration in proper motions for celestial reference frame

Zinovy Malkin

摘要:

近年来,星系自行光行差(GA)的天体测量意义受到了广泛的关注。这种效应在微弧秒级的天体测量中引起系统误差。有些作者认为这是如此严重,它需要重新定义的天体参考系(CRF)。我们认为,对GA的这种关注过于夸张。这只是一个小的天体测量修正,在高精度的天体测量和大地测量数据处理过程中必须考虑。这种校正的准确性取决于银河系旋转参数的准确性,对于大多数应用,取决于银河系和赤道系统之间的旋转矩阵的准确性。我们的分析表明,我们今天对这两个因素的了解足以计算出精度优于10%的GA校正。在几十微弧秒/年的水平上的剩余效应现在可以忽略不计。引入GA校正的另一个后果是需要回到经典的天体测量建模的VLBI导出河外射电源的位置的线性趋势模型。将基于射电源零运动假设的VLBI导出的CRF的当前范例改变为经典范例,导致J2000.0历元星表的射电源位置偏差高达几十微弧秒。

英文摘要:

During the last years, much attention has been paid to the astrometric implications of the galactic aberration in proper motions (GA). This effect causes systematic errors in astrometric measurements at a microarcsecond level. Some authors consider it so serious that it requires redefinition of the celestial reference system (CRF). We argue that such attention to the GA is too much exaggerated. It is just a small astrometric correction that must be taken into account during highly accurate astrometric and geodetic data processing. The accuracy of this correction depends on accuracy of the Galactic rotation parameters and, for most application, on the accuracy of the rotation matrix between Galactic and equatorial systems. Our analysis has shown that our today knowledge of these two factors is sufficient to compute the GA correction with accuracy of better than 10%. The remaining effect at a level of few tenths microarcsecond/yr is negligible nowadays. Another consequence of introducing the GA correction is necessity to return to classical astrometric modeling of the VLBI-derived extragalactic radio source position by the linear trend model. Changing the current paradigm of VLBI-derived CRF based on assumption of zero motion of radio sources to classical one leads to bias in the radio source positions up to several tens microarcseconds for catalog at epoch J2000.0.

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