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A re-interpretation of the definition of UT1

Published online by Cambridge University Press:  03 August 2017

A. T. Sinclair
A. T. Sinclair*
Affiliation:
Royal Greenwich Observatory, Herstmonceux Castle, Hailsham, East Sussex. BN27 1RP. England

Summary

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Universal time is a commonplace quantity, and yet it has no generally accepted definition. The expression for sidereal time is often quoted as a definition, but this does not convey much meaning to the average person. Also sidereal time is measured from the equinox of date, and so involves the precession formulae of the stellar reference frame, and hence may not be ideal for other modern techniques of observation. Guinot (1979) has proposed a broad definition of UT1:

“UT1 is an angle which is proportional to the sidereal rotation of the Earth, the coefficient of proportionality being chosen so that UT1, in the long term, remains in phase with the alternation of day and night. In some applications, UT1 can be considered as a non-uniform time scale”.

Type
I. Celestial Reference Systems
Information
Symposium - International Astronomical Union , Volume 128: Earth's Rotation and Reference Frames for Geodesy and Geodynamics , 1988 , pp. 39 - 40
Copyright
Copyright © Reidel 1988 

References

Aoki, S., Guinot, B., Kaplan, G.H., Kinoshita, H., McCarthy, D.D., and Seidelmann, P.K., 1982, Astron. Astrophys. 105, 359–361.Google Scholar
Guinot, B., 1979. Time and the Earth's Rotation, McCarthy, D.D. and Pilkington, J.D.H., 7–18.CrossRefGoogle Scholar
Xu, B., Zhu, S., Zhang, H., 1986, Astrometric Techniques, Eichhorn, H.K. and Leacock, R.J., 13–17.CrossRefGoogle Scholar