rv = ERFA.fapa03(t)
Fundamental argument, IERS Conventions (2003): general accumulated precession in longitude.
t double TDB, Julian centuries since J2000.0 (Note 1)
double general precession in longitude, radians (Note 2)
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Though t is strictly TDB, it is usually more convenient to use TT, which makes no significant difference.
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The expression used is as adopted in IERS Conventions (2003). It is taken from Kinoshita & Souchay (1990) and comes originally from Lieske et al. (1977).
Kinoshita, H. and Souchay J. 1990, Celest.Mech. and Dyn.Astron. 48, 187
Lieske, J.H., Lederle, T., Fricke, W. & Morando, B. 1977, Astron.Astrophys. 58, 1-16
McCarthy, D. D., Petit, G. (eds.), IERS Conventions (2003), IERS Technical Note No. 32, BKG (2004)
This revision: 2021 May 11
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