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Journal of Astrophysics and Astronomy

, Volume 29, Issue 3–4, pp 363–366 | Cite as

Error minimization of polynomial approximation of Delta T

  • Islam Sana
  • Sadiq Muhammad
  • Qureshi Muhammad Shahid
Article
  • 40 Downloads

Abstract

The difference between Universal time (UT) and Dynamical time (TD), known as Delta T (ΔT) is tabulated for the first day of each year in the Astronomical Almanac. During the last four centuries it is found that there are large differences between its values for two consecutive years. Polynomial approximations have been developed to obtain the values of ΔT for any time of a year for the period AD 1620 to AD 2000 (Meeu 2000) as no dynamical theories describe the variations in ΔT. In this work, a new set of polynomials for ΔT is obtained for the period AD 1620 to AD 2007 that is found to produce better results compared to previous attempts.

Key words

Delta T polynomial approximation Dynamical time Universal time 

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References

  1. Guinot, B., Seidelmann, P. K. 1998, Time scales: their history, definition and interpretation, Astron. Astrophys., 194, 304–308.ADSGoogle Scholar
  2. Husfeld, D., Kronberg, C. 1996, Astronomical Time Keeping, http://www.maa.mhn.de/Scholar/times.html.
  3. McCarthy, D. D. 2004, Precision time and the rotation of the Earth, International Astronomical Union, Washington, DC 20392, USA, e-mail: dmc@maia.usno.navy.mil.Google Scholar
  4. Meeus J. 1998a, Astronomical algorithms, Willmann-Bell, 2nd edn., Chapter 10 (Dynamical time and universal time).Google Scholar
  5. Meeus, J. 1998b, The effect of Delta T on astronomical calculation, Br. Asstron. Assoc., 108(3), 154–156.ADSGoogle Scholar
  6. Meeus, J., Simons, L. 2000, Polynomial Approximation of Delta T, Br. Asstron. Assoc., 110, 323–324.ADSGoogle Scholar
  7. Nelson, R. A., McCarthy, D. D., Malys, S., Levine, J., Guinot, B., Fliegel, H. F., Beard, R. L., Bartholomew, T. R. 2001, The leap second: Its history and possible future, Metrologia, 38, 509–529.CrossRefADSGoogle Scholar
  8. Robert, H. 2002, Delta T: Approximate algorithms for historical periods, http://www.phys.uu.nl/~vgent/astro/deltatime.htm.
  9. Seidelmann, P. K. 1985, Fundamental reference system; past, present, and future celestial mechanics, 37, 199–207Google Scholar

Copyright information

© Indian Academy of Sciences 2008

Authors and Affiliations

  • Islam Sana
    • 1
  • Sadiq Muhammad
    • 1
  • Qureshi Muhammad Shahid
    • 2
  1. 1.Department of Applied PhysicsUniversity of KarachiKarachiPakistan
  2. 2.Institute of Space and Planetary AstrophysicsUniversity of KarachiKarachiPakistan

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