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


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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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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