Chapter 8. Dynamical and Coordinate Time Scales

  1. Prof. Dennis D. McCarthy1 and
  2. Prof. P. Kenneth Seidelmann2

Published Online: 12 FEB 2010

DOI: 10.1002/9783527627943.ch8

Time - From Earth Rotation to Atomic Physics

Time - From Earth Rotation to Atomic Physics

How to Cite

McCarthy, D. D. and Seidelmann, P. K. (2009) Dynamical and Coordinate Time Scales, in Time - From Earth Rotation to Atomic Physics, Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim, Germany. doi: 10.1002/9783527627943.ch8

Author Information

  1. 1

    U.S. Naval Observatory, Washington DC, USA

  2. 2

    University of Virginia, Astronomy Department, Charlottesville, VA, USA

Publication History

  1. Published Online: 12 FEB 2010
  2. Published Print: 14 OCT 2009

ISBN Information

Print ISBN: 9783527407804

Online ISBN: 9783527627943



  • Barycentric Dynamical Time (TDB);
  • Ephemeris Time (ET);
  • Terrestrial Time (TT);
  • Geocentric Coordinate Time (TCG);
  • Barycentric Coordinate Time (TCB);
  • Barycentric Ephemeris Time (Teph)


This chapter contains sections titled:

  • Replacing Ephemeris Time

  • Terrestrial Dynamical Time (TDT) and Barycentric Dynamical Time (TDB)

  • Problems with TDT and TDB

  • New Reference System

  • New Time Scales

  • ΔT and Ephemeris Time Revised

  • Relationships Among Coordinate Time Scales

  • References