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A Re-examination of the Star Observation in Early Ming Dynasty Based on the Star Catalogue of \textit{Datong Tongzhan}-with Discussion on the Changes of Traditional Chinese Constellations

Chu, L. F.; Yang, B. S.

\textit{Datong Tongzhan} is a divination book compiled by the Imperial Board of Astronomy in early Ming dynasty, which preserves some positional data of stars observed at that time. Based on this star catalogue, a further research is carried out on star observation in early Ming dynasty. Firstly, through a deep analysis, it is found that this book…

Overall Properties of the ICRF and Gaia-CRF

Liu, N.

The International Celestial Reference System (ICRS) now has realizations at several frequencies, all with an accuracy of several tens of mircoarcsecond (µas) level, including the International Celestial Reference Frame (ICRF) based on observations of the very long baseline interferometry (VLBI) at S/X, K, and X/Ka band, and the Gaia celestia…

Hunting for Long-lived Protoplanetary Disks Observed with AKARI/FIS

Liu, Y.; Liu, Q.

Twenty-one YSOs (Young Stellar Objects) in the solar neighbor have been identified through cross-correlating Hipparcos catalog with AKARI/FIS YSO catalog. The reliability of the match is over 90%. The central objects cover spectral types from B to M. The Hipparcos parallaxes enable us to place the objects in the H-R diagram, which can be used to d…

Determination of Reference Catalogs for Meridian Observations Using Statistical Method

Li, Z. Y.

The meridian observational data are useful for developing high-precision planetary ephemerides of the solar system. These historical data are provided by the jet propulsion laboratory (JPL) or the Institut De Mecanique Celeste Et De Calcul Des Ephemerides (IMCCE). However, we find that the reference systems (realized by the fundamental catalogs FK…

A Research on the New Astronomical Reference Systems

Liu, J. C.

The research of astrometry encompasses all that is necessary to provide the positions and motions of celestial bodies, including observational techniques, instrumentations, processing and analysis of the observational data, reference systems and so on. In the latest decades, great progress has been made in astrometry, including the new theoretical…

Binary Orbit Determination by Using a Variety of Observational Data

Ren, S. L.

The binary orbit determination is a basic research area in astronomy, its main products are the kinematical parameters of binary, which contain the kinematical parameters of the mass center and the orbital parameters. These parameters are the necessary constituents of the astronomical reference frame with high precision and high density, and at th…

A Kinematical Study for the Galaxy Based on the Revised Hipparcos Astrometric Data

Zhang, H.; Shen, M.

On the basis of the revised Hipparcos data recently released, the zero-point of the PL relation for classical cepheids was reexamined. Fitting proper motion and radial velocity data via an axis symmetric model, Oort constants and circular rotation velocity of the LSR were calculated to obtain Galactocentric distance of the sun, R0 = 8.0±0.8 kpc. F…

Scale height of the thin galactic disk in solar neighborhood

Zhu, Z.; Kong, D. L.

Thanks to astrometric data of unprecedented accuracy from Hipparcos Catalogue

(ESA 1997), it becomes possible to investigate, by directly counting stars, the scale height of the thin Galactic disk in solar neighborhood defined by the perpendicular distribution of stellar populations. In order to trace out the evolution of scale height, which …

A method of determining binary orbits by incorporating long-term observational data

Fu, Y. N.; Ren, S. L.

Early ground based observations accumulated a large amount of long-term data about binary stellar systems. Compared with the data obtained by various present-day techniques, the early data have much lower precision. However, the span of the longer time interval makes these data still irreplaceable in certain astronomical researches. The present wo…

Precessional correction and the proper-motion systems of FK5 and Hipparcos

Zhu, Z.

Comparing proper motions of the FK5 and Hipparcos, several authors declared that the two proper-motion systems are inconsistent with the value of the precessional correction obtained from VLBI and LLR observations. Based on the proper-motion data from the PPM and ACRS catalogues which are constructed on the FK5 system, the discrepant values of the…