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SUBROUTINE sla_MAPQKZ (RM, DM, AMPRMS, RA, DA)
*+
* - - - - - - -
* M A P Q K Z
* - - - - - - -
*
* Quick mean to apparent place: transform a star RA,Dec from
* mean place to geocentric apparent place, given the
* star-independent parameters, and assuming zero parallax
* and proper motion.
*
* 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.
*
* The corresponding routine for the case of non-zero parallax
* and proper motion is sla_MAPQK.
*
* The reference frames and timescales used are post IAU 1976.
*
* Given:
* RM,DM d mean RA,Dec (rad)
* AMPRMS d(21) star-independent mean-to-apparent parameters:
*
* (1-4) not used
* (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
*
* Returned:
* RA,DA d apparent RA,Dec (rad)
*
* References:
* 1984 Astronomical Almanac, pp B39-B41.
* (also Lederle & Schwan, Astron. Astrophys. 134,
* 1-6, 1984)
*
* Notes:
*
* 1) The vectors AMPRMS(2-4) and AMPRMS(5-7) are referred to the
* mean equinox and equator of epoch EQ.
*
* 2) 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 920 arcsec of the
* centre of the Sun's disc. The term has a maximum value of
* about 1.85 arcsec at this radius, and decreases to zero as
* the centre of the disc is approached.
*
* Called: sla_DCS2C, sla_DVDV, sla_DMXV, sla_DCC2S, sla_DRANRM
*
* P.T.Wallace Starlink 18 March 1999
*
* Copyright (C) 1999 Rutherford Appleton Laboratory
*-
IMPLICIT NONE
DOUBLE PRECISION RM,DM,AMPRMS(21),RA,DA
INTEGER I
DOUBLE PRECISION GR2E,AB1,EHN(3),ABV(3),
: P(3),PDE,PDEP1,W,P1(3),P1DV,
: P1DVP1,P2(3),P3(3)
DOUBLE PRECISION sla_DVDV,sla_DRANRM
* Unpack scalar and vector parameters
GR2E = AMPRMS(8)
AB1 = AMPRMS(12)
DO I=1,3
EHN(I) = AMPRMS(I+4)
ABV(I) = AMPRMS(I+8)
END DO
* Spherical to x,y,z
CALL sla_DCS2C(RM,DM,P)
* Light deflection
PDE = sla_DVDV(P,EHN)
PDEP1 = PDE+1D0
W = GR2E/MAX(PDEP1,1D-5)
DO I=1,3
P1(I) = P(I)+W*(EHN(I)-PDE*P(I))
END DO
* Aberration
P1DV = sla_DVDV(P1,ABV)
P1DVP1 = P1DV+1D0
W = 1D0+P1DV/(AB1+1D0)
DO I=1,3
P2(I) = (AB1*P1(I)+W*ABV(I))/P1DVP1
END DO
* Precession and nutation
CALL sla_DMXV(AMPRMS(13),P2,P3)
* Geocentric apparent RA,Dec
CALL sla_DCC2S(P3,RA,DA)
RA = sla_DRANRM(RA)
END
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