ERFA.ab(pnat, v, s, bm1)Apply aberration to transform natural direction into proper direction.
pnat double[3] natural direction to the source (unit vector) v double[3] observer barycentric velocity in units of c s double distance between the Sun and the observer (au) bm1 double sqrt(1-|v|^2): reciprocal of Lorenz factor
ppr double[3] proper direction to source (unit vector)
- The algorithm is based on Expr. (7.40) in the Explanatory Supplement (Urban & Seidelmann 2013), but with the following changes:
o Rigorous rather than approximate normalization is applied.
o The gravitational potential term from Expr. (7) in Klioner (2003) is added, taking into account only the Sun's contribution. This has a maximum effect of about 0.4 microarcsecond.
- In almost all cases, the maximum accuracy will be limited by the supplied velocity. For example, if the ERFA eraEpv00 function is used, errors of up to 5 microarcseconds could occur.
Urban, S. & Seidelmann, P. K. (eds), Explanatory Supplement to the Astronomical Almanac, 3rd ed., University Science Books (2013).
Klioner, Sergei A., "A practical relativistic model for micro- arcsecond astrometry in space", Astr. J. 125, 1580-1597 (2003).
eraPdp scalar product of two p-vectors
This revision: 2021 February 24
Copyright (C) 2013-2021, NumFOCUS Foundation. Derived, with permission, from the SOFA library.