Chapter 5: Transformation between the International Terrestrial Reference System and Geocentric Celestial Reference System

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Software

  • Routines that support the transformations described in Chapter 5 (see Section 5.9) are included in the SOFA collection.
  • PMSDNUT2.F - Subroutine to compute the diurnal lunisolar effect on polar motion.
    • Based on the subroutine PMsdnut.[1] Differences between the two subroutines are typically smaller than 0.1 μas.
  • UTLIBR.F - Subroutine to compute the subdiurnal librations in UT1.[1]
  • FUNDARG.F - Subroutine to compute the lunisolar fundamental arguments.[2]
  • FCNNUT.F - Computes corrections to the coordinates of the CIP to account for Free Core Nutation. Contains data table to be updated each year. [3] (Updated 10 August 2012)

Additional Information

  • Table 5.2a - IAU 2006/2000A expression of the X coordinate of the CIP in the GCRS.[4]
  • Table 5.2b - IAU 2006/2000A expression of the Y coordinate of the CIP in the GCRS.[4]
  • Table 5.2d - IAU 2006/2000A expression of the quantity s(t) + XY/2.[4]
  • Table 5.2e - IAU 2006/2000A expression for Greenwich Sidereal Time GST.[4]
  • Table 5.2f - Expression for the difference between the IAU 2006 (or IAU 2000A_R06) and IAU 2000 expression for various quantities (X, Y, Dpsi, Deps, s+XY/2).[4]
  • Table 5.3a - Nutation in longitude (IAU 2000_R06 expression) derived from the IAU 2000A lunisolar and planetary components with slight IAU 2006 adjustments.[4]
  • Table 5.3b - Nutation in obliquity (IAU 2000_R06 expression) derived from the IAU 2000A lunisolar and planetary components with slight IAU 2006 adjustments.[4]

[1] Provided by A. Brzezinski.

[2] From the model by Simon et al. (1994).

[3] Provided by S. Lambert

[4] Provided by N. Capitaine