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      SUBROUTINE slAMP (RA, DA, DATE, EQ, RM, DM)

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      A M P
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  Convert star RA,Dec from geocentric apparent to mean place

  The mean coordinate system is the post IAU 1976 system,
  loosely called FK5.

  Given:
     RA       d      apparent RA (radians)
     DA       d      apparent Dec (radians)
     DATE     d      TDB for apparent place (JD-2400000.5)
     EQ       d      equinox:  Julian epoch of mean place

  Returned:
     RM       d      mean RA (radians)
     DM       d      mean Dec (radians)

  References:
     1984 Astronomical Almanac, pp B39-B41.
     (also Lederle & Schwan, Astron. Astrophys. 134,
      1-6, 1984)

  Notes:

  1)  The distinction between the required TDB and TT is
      always negligible.  Moreover, for all but the most
      critical applications UTC is adequate.

  2)  The accuracy is limited by the routine slEVP, called
      by slMAPA, which computes the Earth position and
      velocity using the methods of Stumpff.  The maximum
      error is about 0.3 milliarcsecond.

  3)  Iterative techniques are used for the aberration and
      light deflection corrections so that the routines
      slAMP (or slAMPQ) and slMAP (or slMAPQ) are
      accurate inverses;  even at the edge of the Sun's disc
      the discrepancy is only about 1 nanoarcsecond.

  4)  Where multiple apparent places are to be converted to
      mean places, for a fixed date and equinox, it is more
      efficient to use the slMAPA routine to compute the
      required parameters once, followed by one call to
      slAMPQ per star.

  Called:  slMAPA, slAMPQ

  P.T.Wallace   Starlink   19 January 1993

  Copyright (C) 1995 Rutherford Appleton Laboratory
  Copyright (C) 1995 Association of Universities for Research in Astronomy Inc.

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