Book contents
- Time: From Earth Rotation to Atomic Physics
- Time: From Earth Rotation to Atomic Physics
- Copyright page
- Dedication
- Contents
- Preface
- 1 Time Before the 20th Century
- 2 Time from the Earth’s Rotation
- 3 Ephemerides
- 4 Variable Earth Rotation
- 5 Earth Orientation
- 6 Ephemeris Time
- 7 Relativity and Time
- 8 Time and Cosmology
- 9 Dynamical and Coordinate Timescales
- 10 Clock Developments
- 11 Microwave Atomic Clocks
- 12 Optical Atomic Standards
- 13 Definition and Role of a Second
- 14 International Atomic Time (TAI)
- 15 Coordinated Universal Time (UTC)
- 16 Time in the Solar System
- 17 Time and Frequency Transfer
- 18 Modern Earth Orientation
- 19 International Activities
- 20 Time Applications
- 21 Future of Timekeeping
- Acronyms
- Glossary
- Index
- References
14 - International Atomic Time (TAI)
Published online by Cambridge University Press: 01 October 2018
Book contents
- Time: From Earth Rotation to Atomic Physics
- Time: From Earth Rotation to Atomic Physics
- Copyright page
- Dedication
- Contents
- Preface
- 1 Time Before the 20th Century
- 2 Time from the Earth’s Rotation
- 3 Ephemerides
- 4 Variable Earth Rotation
- 5 Earth Orientation
- 6 Ephemeris Time
- 7 Relativity and Time
- 8 Time and Cosmology
- 9 Dynamical and Coordinate Timescales
- 10 Clock Developments
- 11 Microwave Atomic Clocks
- 12 Optical Atomic Standards
- 13 Definition and Role of a Second
- 14 International Atomic Time (TAI)
- 15 Coordinated Universal Time (UTC)
- 16 Time in the Solar System
- 17 Time and Frequency Transfer
- 18 Modern Earth Orientation
- 19 International Activities
- 20 Time Applications
- 21 Future of Timekeeping
- Acronyms
- Glossary
- Index
- References
Summary
As atomic clocks became available in laboratories and observatories around the world atomic timescales were developed. The Bureau International de l'Heure began an atomic time scale in July 1955 based on clock comparisons at other locations. The IAU recommended a unification of an atomic timescale in 1967, and in 1971, the Conférence Générale des Poids et Mesures (CGPM) requested the definition of International Atomic Time (TAI), and the methods and weighting for the determination of TAI have evolved over the years along with the organizations participating in the process. Coordinated Universal Time (UTC) differs from TAI by integral seconds, so that TAI can be accessed through the international standard UTC. TAI can be considered as a realization of Terrestrial Time (TT).
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- Information
- Time: From Earth Rotation to Atomic Physics , pp. 225 - 248Publisher: Cambridge University PressPrint publication year: 2018
References
Arias, E. F. (2012). Perspective: Time Scales and Clocks: Invited Review Article: The Statistical Modeling of Atomic Clocks and the Design of Time Scales. Review of Scientific Instruments, 83, 020901.Google Scholar
Arias, E. F. (2014). Atomic Time Scales for the 21st Century. Rev Mex AA(Serie de Conferencias), 43, 29–34.Google Scholar
Audoin, C. & Guinot, B. (2001). The Measurement of Time. Cambridge: Cambridge University Press.Google Scholar
Azoubib, J., Granveaud, M., & Guinot, B. (1977). Estimation of the Scale Unit Duration of Time Scales. Metrologia, 13, 87–93.Google Scholar
Barnes, J. A., Andrews, D. H., & Allan, D. W. (1965). The NBS-A Time Scale: Its Generation and Dissemination. IEEE Trans. Instrum. Meas., IM, 14, 228–232.CrossRefGoogle Scholar
Bureau International de l’Heure (1974). BIH Annual Report for 1973. Observatoire de Paris (in French; English version appears in BIH Annual Report for 1974, published in 1975).Google Scholar
Bureau International des Poids et Mesures (2006). The International System of Units (SI). Eighth Edition. Paris: Bureau International des Poids et Mesures.Google Scholar
Bureau International des Poids et Mesures (2016). BIPM Annual Report on Time Activities Volume 10 2015. Paris: Bureau International des Poids et Mesures.Google Scholar
Comptes Rendus de la 14e CGPM (1971) (1972). 78, available at www1.bipm.org/en/convention/cgpm/resolutions.html.Google Scholar
Comptes Rendus de la 15e CGPM (1975) (1976). 104, available at www1.bipm.org/en/convention/cgpm/resolutions.html.Google Scholar
Comptes Rendus de la 18e CGPM (1987) (1988). 98, available at www1.bipm.org/en/convention/cgpm/resolutions.html.Google Scholar
Essen, L. Time for Reflection. Published privately and available at www.btinternet.com/~time.lord/ also available in Henderson, D. (2005). Essen and the National Physical Laboratory’s Atomic Clock. Metrologia, 42 S4–S9.Google Scholar
Essen, L. & Parry, J. V. L. (1957). The Caesium Resonator as a Standard of Frequency and Time. Philos. Trans. Roy. Soc. London. Ser. A, Mathematical and Physical Sciences, 250, 45–69.Google Scholar
Guinot, B. (1988). Atomic Time Scales for Pulsar Studies and Other Demanding Applications. Astron. Astrophys, 192, 370–373.Google Scholar
Guinot, B. & Arias, E. F. (2005). Atomic Time-Keeping from 1955 to the Present. Metrologia, 42, S20–S30.Google Scholar
Levine, J. (2012). The Statistical Modeling of Atomic Clocks and the Design of Time Scales. Review of Scientific Instruments, 83, 021101.Google Scholar
Nelson, R. A., McCarthy, D. D., Malys, S., Levine, J., Guinot, B., Fliegel, H. F., Beard, R. L., & Bartholomew, E. R. (2001). The Leap Second: Its History and Possible Future. Metrologia, 38, 509–529.Google Scholar
Panfilo, G., Harmegnies, A., & Tisserand, L. (2012). A New Prediction Algorithm for the Generation of International Atomic Time. Metrologia, 49, 49–56.CrossRefGoogle Scholar
Panfilo, G., Harmegnies, A., & Tisserand, L. (2014). A New Weighting Procedure for UTC. Metrologia, 51, 285–292.Google Scholar
Petit, G. (2000). Use of Primary Frequency Standards for Estimating the Duration of the Scale Unit of TAI. 31st Annual Precise Time and Time Interval (PTTI) Meeting, 297–304.Google Scholar
Petit, G. (2010). Atomic Time Scales TAI and TT (BIPM): Present Performances and Prospects. Highlights of Astronomy, 15, XXVIIth IAU General Assembly, 220–221.Google Scholar
Petit, G. & Arias, E. F. (2015). Long Term Stability of Atomic Time Scales. Highlights of Astronomy, 16, 209–210.Google Scholar
Tavella, P. & Thomas, C. (1991). Comparative Study of Time Scale Algorithms. Metrologia, 28, 57–63.CrossRefGoogle Scholar
Thomas, C. & Azoubib, J. (1996). TAI Computation: Study of an Alternative Choice for Implementing an Upper Limit of Clock Weights. Metrologia, 33, 227–240.Google Scholar
Trans. Int. Astron. Union (1962), Vol. XI A, Reports on Astronomy. Edited by Sadler, D. H.. New York, NY: Academic Press, 362–363.Google Scholar
Trans. Int. Astron. Union (1991), Vol. XXI B, Reports on Astronomy. Edited by McNally, D.. New York, NY: Academic Press, 362–363.Google Scholar