Transform star RA,Dec from mean place to geocentric apparent. The reference frames and timescales used are post IAU 1976.
1984 Astronomical Almanac, pp b39-b41. (also Lederle & Schwan, Astron. Astrophys. 134, 1-6, 1984)
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) eq double epoch and equinox of star data (Julian) date double TDB for apparent place (JD-2400000.5)
*ra,*da double apparent RA,Dec (rad)
slaMappa star-independent parameters slaMapqk quick mean to apparent
1) eq is the Julian epoch specifying both the reference frame and the epoch of the position - usually 2000. For positions where the epoch and equinox are different, use the routine slaPm to apply proper motion corrections before using this routine. 2) The distinction between the required TDB and TDT is always negligible. Moreover, for all but the most critical applications UTC is adequate. 3) The proper motions in RA are dRA/dt rather than cos(dec)*dra/dt. 4) This routine may be wasteful for some applications because it recomputes the Earth position/velocity and the precession/nutation matrix each time, and because it allows for parallax and proper motion. Where multiple transformations are to be carried out for one epoch, a faster method is to call the slaMappa routine once and then either the slaMapqk routine (which includes parallax and proper motion) or slaMapqkz (which assumes zero parallax and proper motion). P.T.Wallace Starlink 30 October 1993