Hostname: page-component-586b7cd67f-dsjbd Total loading time: 0 Render date: 2024-11-29T23:58:37.609Z Has data issue: false hasContentIssue false
  • English
  • Français

Observations of the Celestial Ephemeris Pole

Published online by Cambridge University Press:  30 March 2016

R.S. Gross
R.S. Gross*
Affiliation:
Jet Propulsion LaboratoryCalifornia Institute of TechnologyPasadena, California 91109 P8099, USA

Abstract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

Space-geodetic measurement systems are capable of determining: (1) a terrestrial, body-fixed reference frame defined in practice by the stated positions and secular motions of a set of observing stations, (2) a celestial, space-fixed reference frame defined in practice by the stated locations of celestial objects, and (3) the rotation parameters linking these two frames together. Five parameters are conventionally used to specify the orientation of the terrestrial frame with respect to the celestial frame: two nutation parameters, two polar motion parameters, and one spin parameter. The celestial ephemeris pole (CEP) is defined as the north pole of that axis about which the spin parameter (UT1) is measured. The two nutation parameters locate the CEP in the celestial frame, and the two polar motion parameters locate the CEP in the terrestrial frame. By examining the frame transformation matrices, an expression relating the location of the rotation pole to that of the CEP can be derived. In order to compare theoretical predictions with observations, results of models for the effect on the nutations of geophysical excitation processes such as diurnal oceanic current and sea level height variations should not only be given in terms of the location of the CEP (rather than of the rotation pole), but must also account for the resonance effects of the free core nutation.

Type
II. Joint Discussions
Information
Highlights of Astronomy , Volume 10: Highlights of Astronomy. As presented at the XXIInd General Assembly of the IAU, 1994 , 1995 , pp. 232 - 236
Copyright
Copyright © Kluwer 1995

References

Aoki, S., Guinot, B., Kaplan, G.H., Kinoshita, H., McCarthy, D.D. and Seidelmann, P.K. (1982) The new definition of universal time, Astron. Astrophys., Vol. 105, pp. 359–361.Google Scholar
Brzezinski, A. (1994) Polar motion excitation by variations of the effective angular momentum function, II: Extended-model, Manuscripta Geodaetica, Vol. 19, pp. 157–171.Google Scholar
Brzezinski, A. and Capitaine, N. (1993) The use of the precise observations of the celestial ephemeris pole in the analysis of geophysical excitation of Earth rotation, J. Geophys. Res., Vol. 98, pp. 6667–6675.Google Scholar
Gross, R.S. (1992) Correspondence between theory and observations of polar motion, Geophys. J. Int., Vol. 109, pp. 162–170.Google Scholar
Gross, R.S. (1993) The effect of ocean tides on the Earth’s rotation as predicted by the results of an ocean tide model, Geophys. Res. Lett., Vol. 20, pp. 293–296.Google Scholar
Mathews, P.M., Buffett, B.A., Herring, T.A., Shapiro, I.I. (1991) Forced nutations of the Earth: Influence of inner core dynamics 2. Numerical results and comparisons, J. Geophys. Res., Vol. 96, pp. 8243–8257.Google Scholar
Sasao, T. and Wahr, J.M. (1981) An excitation mechanism for the free ‘core nutation’, Geophys. J. Roy. astr. Soc., Vol. 64, pp. 729–746.Google Scholar
Seller, U. (1991) Periodic changes of the angular momentum budget due to the tides of the world ocean, J. Geophys. Res., Vol. 96, pp. 10287–10300.CrossRefGoogle Scholar
Sovers, O.J. and Jacobs, C.S. (1994) Observation model and parameter partials for the JPL VLBI parameter estimation software “MODEST” Q1994, JPL Publication 83-39, Rev. Vol. 5, Jet Propulsion Laboratory, Pasadena, California.Google Scholar