**ACTION:**- Quick mean to apparent place: transform a star from
mean place to geocentric apparent place, given the
star-independent parameters, and assuming zero parallax
and FK5 proper motion.
The reference frames and timescales used are post IAU 1976.
**CALL:**`CALL sla_MAPQKZ (RM, DM, AMPRMS, RA, DA)`

**GIVEN:**-

*RM,DM***D**mean (radians) *AMPRMS***D(21)**star-independent mean-to-apparent parameters: (1) time interval for proper motion (Julian years) (2-4) barycentric position of the Earth (AU) (5-7) heliocentric direction of the Earth (unit vector) (8) (gravitational radius of Sun)(Sun-Earth distance) (9-11) **v**: barycentric Earth velocity in units of c(12) (13-21) precession/nutation matrix

**RETURNED:**-

*RA,DA***D**apparent (radians)

**NOTES:**- 1.
- Use of this routine is appropriate when efficiency is important and where many star positions, all with parallax and proper motion either zero or already allowed for, and 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 sla_MAPPA routine.
- 2.
- The corresponding routine for the case of non-zero parallax and FK5 proper motion is sla_MAPQK.
- 3.
- The vectors AMPRMS(2-4) and AMPRMS(5-7) are referred to the mean equinox and equator of epoch EQ.
- 4.
- Strictly speaking, the routine is not valid for solar-system sources, though the error will usually be extremely small. However, to prevent gross errors in the case where the position of the Sun is specified, the gravitational deflection term is restrained within about of the centre of the Sun's disc. The term has a maximum value of about at this radius, and decreases to zero as the centre of the disc is approached.

**REFERENCES:**- 1.
- 1984
*Astronomical Almanac*, pp B39-B41. - 2.
- Lederle & Schwan, 1984.
*Astr.Astrophys.***134**, 1-6.

Starlink User Note 67

P. T. Wallace

12 October 1999

E-mail:ptw@star.rl.ac.uk