Definition of the Celestial Ephemeris Pole and the Celestial Ephemeris Origin
Abstract
The International Celestial Reference System (ICRS), which was adopted by the International Astronomical Union (IAU) and in use since 1 January 1998, and the accuracy achieved by the most recent models and observations of Earth rotation call for a redefinition of the Earth Orientation Parameters (EOP). First, the precession-nutation parameters and Greenwich sidereal time, which are currently defined in the FK5 System, have to be re-defined to be consistent with the ICRS. Second, the current definition of the Celestial Ephemeris Pole (CEP) has to be extended to be consistent with the most recent models for nutation and polar motion at microarcsecond accuracy, including diurnal and sub-diurnal components, as well as with new strategies of observations. Such issues have been under consideration by the subgroup T5 named "Computational Consequences" of the IAU Working Group ICRS. This paper gives, as the basis for future recommendations, the preliminary proposals of the subgroup T5 for a modern definition of the CEP, for the definition of more basic EOP in the ICRS, and for the choice of a new origin on the equator of the CEP in place of the equinox. The paper also emphasizes the use of the Celestial Ephemeris Origin (CEO), which is defined as the "non-rotating origin" in the celestial frame on the equator of the CEP.
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 01, 2000
- Accession Number
- ADA435813
Entities
People
- Nicole Capitaine
Organizations
- Paris Observatory, PSL University