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A Method to Improve Binary Orbits by Incorporating Long-term Observational Data

Ren, Shu-lin; Fu, Yan-ning

Early ground-based observations have accumulated a large volume of data on binary stellar systems. Compared to the more recent data obtained by various new techniques, these older data have both the disadvantage of low precision and the advantage of long time-span. For long-period binary systems having available both long-term data and Hipparcos d…

Precession Constant Correction and Proper Motion Systems of FK5 and Hipparcos

Zhu, Zi

Results of many researches have shown that the relation between the proper motion systems of FK5 and Hipparcos is not consistent with the precession constant corrections determined by VLBI and LLR. We analysed proper motion data of PPM and ACRS based on the FK5 system for many different sub-samples and found that consistent values of the precessio…