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Astron. Astrophys. 343, 624-633 (1999)

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Determination of the lunar orbital and rotational parameters and of the ecliptic reference system orientation from LLR measurements and IERS data

J. Chapront, M. Chapront-Touzé and G. Francou

Observatoire de Paris/DANOF - CNRS/URA 1125, 61 avenue de l'Observatoire, F-75014 Paris, France

Received 27 April 1998 / Accepted 7 December 1998


An analysis of Lunar Laser Ranging (LLR) observations from January 1972 till March 1998 is performed using the lunar theory ELP 2000-96 and the completed Moons' theory of the lunar libration. The LLR station coordinates, polar motion and Universal Time are provided by the International Earth Rotation Service (IERS). In Solution 1 the precession-nutation transformation is given by recent analytical theories, while in Solution 2 it is derived from the IERS daily corrections. Orbital and free libration parameters of the Moon, and coordinates of the reflectors are obtained in both cases. The position of the inertial mean ecliptic of J2000.0 with respect to the equator of the mean Celestial Ephemeris Pole (CEP) of J2000.0 (in Solution 1) and to the International Celestial Reference System (ICRS), the IERS celestial reference system, (in Solution 2) are fit. The position of the mean CEP equator of J2000.0 and of several dynamical reference planes and origins, with respect to ICRS, are derived from these fits (Fig. 1). The leading results are the following: [FORMULA] (in the equator) for the separation of the origin of right ascensions in ICRS from the ascending node of the inertial mean ecliptic of J2000.0 on the reference plane of ICRS, [FORMULA] (in the ecliptic) for the separation of the latter point from the inertial dynamical mean equinox of J2000.0, [FORMULA] (in the equator) for the separation of the inertial dynamical mean equinox of J2000.0 from the J2000.0 right ascension origin derived from IERS polar motion and Universal Time and from precise theories of precession-nutation, and [FORMULA] for the inertial obliquity of J2000.0. A correction of [FORMULA] to the IAU 1976 value of the precession constant is also obtained (the errors quoted are formal errors).

Key words: ephemerides – reference systems – Moon

Send offprint requests to: J. Chapront

© European Southern Observatory (ESO) 1999

Online publication: March 1, 1999