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The use of LLR observations (1969-2006) for the determination of the GCRS coordinates of the pole. Inertial mean ecliptic of J2000.0. [CRF] = Q.R.W [TRF]. ε (CIP). ‘ CIP equator. ү I 2000(CIP ). B = P N (Precession Nutation matrix based on the coordinates X,Y of the CIP). O (CIP). Ф.
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The use of LLR observations (1969-2006) for the determination of the GCRS coordinates of the pole Inertial mean ecliptic of J2000.0 [CRF] = Q.R.W [TRF] ε(CIP) ‘ CIP equator үI2000(CIP) B = P N (Precession Nutation matrix based on the coordinates X,Y of the CIP) O (CIP) Ф Wassila Zerhouni (1), Nicole Capitaine (1), Gerard Francou (1) (1) Observatoire de Paris / SYRTE , 61 Avenue de l’Observatoire 75014 Paris Wassila.zerhouni@obspm.fr,Nicole.capitaine@obspm.fr,Gerard.francou@obspm.fr The principle of Lunar Laser Ranging is to fire laser pulses from the telescopes on the Earth toward the reflectors on the Moon, to receive back localised and recognizable signals and to measure the duration of the round trip travel of the light. 3 2 1 The Lunar motion defines intrinsically a dynamical system. It allows in particular the positionning of the inertial mean ecliptic of J2000.0 with respect to the CIP (Celestial Intermediate Pole) and to the ICRS (International Celestial Reference System) using this transformation : Q : Matrix transformation for the motion of the celestial pole in the celestial system R : Matrix transformation for the Earth rotation W : Matrix transformation for the polar motion In previous work (IUGG 2007), we determined the position of the inertial mean ecliptic of J2000.0 with respect to the CIP with this classical transformation : [CRF] = A.B.R.W [TRF] W = R1(yp)R2(xp) B = P N (Precession Nutation matrix based on Δψ and Δε) R = R3(-GST) A = R1(ε)R3(Ф) Ф, ε : cf. fig 1 GST : Greenwitch Sideral Time xp, yp : pole coordinates in the TRF Using LLR observations from McDonald 1969-2006 and Cerga 1984-2005, Capitaine et al.2003 as a model of precession and MHB 2000 for the nutation, we have found : Ф (arcsecond) = -0.01453±0.00010 and ε (arcsecond) =84381.40379±0.00009 In this work, we have done the same investigation with including the conventional model (precession, nutation and frame bias) for the coordinates X and Y of the CIP (Celestial Intermediate Pole) in the GCRS (Geocentric Celestial Reference System) instead of the classical precession nutation parameters. It implies : R = R3(-ERA) Figure 1 • With the same previous data (LLR observations • from 1969 until 2006) and the new transformation • we obtained these residuals (cf. fig 2, fig 3). • Normal points : • Figure 2 : • Top part : 1183 • Bottom part : 8361 • Figure 3 : Top part : 3546 Bottom part : 2870 Figure 3 Figure 2 In a second time, we made a new analysis, we fitted the parameters X and Y. The figure 4 represents the preliminary results obtained with fitted parameters X, Y and their formal errors Figure 4 References : Capitaine et al. 2003, Astron. Astrophys., 412, 567-586. Chapront et al. 2002, Astron. Astrophys., 387, 700-709. Mathews et al.2002, J.Geophys. Res, 107(B4), 10.1029/2001JB00390. McCarthy, D. D. 1996, IERS technical Note 21: IERS Conventions (1996). Williams, J.G.1994,AJ, 108, 2.
