Expressions for IAU 2000 precession quantities

• DOI: 10.1051/0004-6361:20031539
• Publication Date: 2003-11-28T10:06:17Z
• Authors: N. Capitaine; P. T. Wallace; J. Chapront
• Keywords: Nutation; Precession; Longitude; Ephemeris; Celestial mechanics; Ecliptic

A new precession-nutation model for the Celestial Intermediate Pole (CIP) was adopted by IAU in 2000 (Resolution B1.6). The model, designated 2000A, includes a nutation series non-rigid Earth and corrections precession rates longitude obliquity. also specifies numerical values pole offsets at J2000.0 between mean equatorial frame Geocentric Reference System (GCRS). In this paper, we discuss models consistent with 2000A (i.e. MHB 2000, provided Mathews et al. [CITE]) provide range of expressions that implement them. final P03, is possible replacement component offering improved dynamical consistency better basis future improvement. As preliminary step, present our currently used quantities , agreement to rates, appear IERS Conventions 2000. We then more sophisticated method improving equator order it be compliant model. contrast first method, which based on t terms developments obliquity, uses their higher degree terms. It essential conjunction an ecliptic precession, expected, given known discrepancies 1976 expressions, contribute significant way these With aim view, have developed motion respect fixed using from Simon ([CITE]) Williams constants fitted most recent planetary ephemerides. together solve equations providing solution dynamically number perturbing effects been removed estimates get physical needed as integration constants. solved similar Lieske ([CITE]), theoretical contributions revised values. Once obtained equator, suitable considered minimum variables best adapted observations. Finally quantities, denoted P03 solution, including Sidereal Time expression.