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ee00b

sofars::erst

Function ee00b 

Source 
pub fn ee00b(date1: f64, date2: f64) -> f64
Expand description

Equation of the equinoxes, IAU 2000B

Equation of the equinoxes, compatible with IAU 2000 resolutions but using the truncated nutation model IAU 2000B.

This function is part of the International Astronomical Union’s SOFA (Standards of Fundamental Astronomy) software collection.

Status: support function.

Given: date1,date2 double TT as a 2-part Julian Date (Note 1)

Returned (function value): double equation of the equinoxes (Note 2)

Notes:

  1. The TT date date1+date2 is a Julian Date, apportioned in any convenient way between the two arguments. For example, JD(TT)=2450123.7 could be expressed in any of these ways, among others:
          date1          date2

       2450123.7           0.0       (JD method)
       2451545.0       -1421.3       (J2000 method)
       2400000.5       50123.2       (MJD method)
       2450123.5           0.2       (date & time method)

The JD method is the most natural and convenient to use in cases where the loss of several decimal digits of resolution is acceptable. The J2000 method is best matched to the way the argument is handled internally and will deliver the optimum resolution. The MJD method and the date & time methods are both good compromises between resolution and convenience.

  1. The result, which is in radians, operates in the following sense:

    Greenwich apparent ST = GMST + equation of the equinoxes

  2. The result is compatible with the IAU 2000 resolutions except that accuracy has been compromised (1 mas) for the sake of speed. For further details, see McCarthy & Luzum (2003), IERS Conventions 2003 and Capitaine et al. (2003).

Called:

   iauPr00      IAU 2000 precession adjustments
   iauObl80     mean obliquity, IAU 1980
   iauNut00b    nutation, IAU 2000B
   iauEe00      equation of the equinoxes, IAU 2000

References:

Capitaine, N., Wallace, P.T. and McCarthy, D.D., “Expressions to implement the IAU 2000 definition of UT1”, Astronomy & Astrophysics, 406, 1135-1149 (2003)

McCarthy, D.D. & Luzum, B.J., “An abridged model of the precession-nutation of the celestial pole”, Celestial Mechanics & Dynamical Astronomy, 85, 37-49 (2003)

McCarthy, D. D., Petit, G. (eds.), IERS Conventions (2003), IERS Technical Note No. 32, BKG (2004)