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+.help mappa Jun99 "Slalib Package"
+.nf
+
+      SUBROUTINE slMAPA (EQ, DATE, AMPRMS)
+
+     - - - - - -
+      M A P A
+     - - - - - -
+
+  Compute star-independent parameters in preparation for
+  conversions between mean place and geocentric apparent place.
+
+  The parameters produced by this routine are required in the
+  parallax, light deflection, aberration, and precession/nutation
+  parts of the mean/apparent transformations.
+
+  The reference frames and timescales used are post IAU 1976.
+
+  Given:
+     EQ       d      epoch of mean equinox to be used (Julian)
+     DATE     d      TDB (JD-2400000.5)
+
+  Returned:
+     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)      (grav rad Sun)*2/(Sun-Earth distance)
+       (9-11)   ABV: barycentric Earth velocity in units of c
+       (12)     sqrt(1-v**2) where v=modulus(ABV)
+       (13-21)  precession/nutation (3,3) matrix
+
+  References:
+     1984 Astronomical Almanac, pp B39-B41.
+     (also Lederle & Schwan, Astron. Astrophys. 134,
+      1-6, 1984)
+
+  Notes:
+
+  1)  For DATE, 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 of the routines using the parameters AMPRMS is
+      limited by the routine slEVP, used here to compute the
+      Earth position and velocity by the methods of Stumpff.
+      The maximum error in the resulting aberration corrections is
+      about 0.3 milliarcsecond.
+
+  3)  The vectors AMPRMS(2-4) and AMPRMS(5-7) are referred to
+      the mean equinox and equator of epoch EQ.
+
+  4)  The parameters AMPRMS produced by this routine are used by
+      slMAPQ and slMAPZ.
+
+  Called:
+     slEPJ         MDJ to Julian epoch
+     slEVP         earth position & velocity
+     slDVN         normalize vector
+     slPRNU      precession/nutation matrix
+
+  P.T.Wallace   Starlink   23 November 1995
+
+  Copyright (C) 1995 Rutherford Appleton Laboratory
+  Copyright (C) 1995 Association of Universities for Research in Astronomy Inc.
+
+.fi
+.endhelp