Quick mean to apparent place: transform a star RA,Dec from mean place to geocentric apparent place, given the star-independent parameters. Use of this routine is appropriate when efficiency is important and where many star positions, all referred to the same equator and equinox, are to be transformed for one epoch. The star-independent parameters can be obtained by calling the slaMappa routine. If the parallax and proper motions are zero the slaMapqkz routine can be used instead. The reference frames and timescales used are post IAU 1976.
rm,dm double mean RA,Dec (rad) pr,pd double proper motions: RA,Dec changes per Julian year px double parallax (arcsec) rv double radial velocity (km/sec, +ve if receding)
(0) time interval for proper motion (Julian years) (1-3) barycentric position of the Earth (AU) (4-6) heliocentric direction of the Earth (unit vector) (7) (grav rad Sun)*2/(Sun-Earth distance) (8-10) barycentric Earth velocity in units of c (11) sqrt(1-v2) where v=modulus(abv) (12-20) precession/nutation (3,3) matrix
*ra,*da double apparent RA,Dec (rad)
1984 Astronomical Almanac, pp B39-B41. (also Lederle & Schwan, Astron. Astrophys. 134, 1-6, 1984)
1) The vectors amprms(1-3) and amprms(4-6) are referred to the mean equinox and equator of epoch eq. 2) Within about 300 arcsec of the centre of the Sun the gravitational deflection term is set to zero to avoid overflow. Otherwise no account is taken of the impossibility of observing stars which lie behind the Sun.
slaDcs2c spherical to Cartesian slaDvdv dot product slaDmxv matrix x vector slaDcc2s Cartesian to spherical slaDranrm normalize angle 0-2pi Defined in slamac.h: DAS2R P.T.Wallace Starlink 31 October 1993