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An Error in the Determination of ΔT from the Lunar Ephemeris and the Frequency of Caesium in Terms of U.T. + ΔT

Abstract

THE ellipticity of the Earth causes perturbations of the elements of the Moon's orbit with a period of 18.6 years. The value of the ellipticity used in Brown's “Tables of the Motion of the Moon” and in the “Improved Lunar Ephemeris” is 1/294. As has been pointed out elsewhere1, the correction to be applied to the tabular longitude of the Moon in order to reduce it to ellipticity 1/297 is equal to −0.149″ sin Ω, where Ω is the longitude of the Moon's node. This is equivalent to a correction of + 0.271 s. sin Ω to ΔT as defined by the International Astronomical Union2. Recent observations of artificial Earth satellites indicate that the true value of the ellipticity may be nearer 1/298 (ref. 3), in which case the correction to be applied to ΔT is + 0.36 s. sin Ω.

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References

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  2. Trans. Int. Astron. Union, 8, 66 (1954).

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MURRAY, C. An Error in the Determination of ΔT from the Lunar Ephemeris and the Frequency of Caesium in Terms of U.T. + ΔT . Nature 184, 441–442 (1959). https://doi.org/10.1038/184441b0

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