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authorJoe Hunkeler <jhunkeler@gmail.com>2015-08-11 16:51:37 -0400
committerJoe Hunkeler <jhunkeler@gmail.com>2015-08-11 16:51:37 -0400
commit40e5a5811c6ffce9b0974e93cdd927cbcf60c157 (patch)
tree4464880c571602d54f6ae114729bf62a89518057 /math/slalib/ampqk.f
downloadiraf-osx-40e5a5811c6ffce9b0974e93cdd927cbcf60c157.tar.gz
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+ SUBROUTINE slAMPQ (RA, DA, AMPRMS, RM, DM)
+*+
+* - - - - - -
+* A M P Q
+* - - - - - -
+*
+* Convert star RA,Dec from geocentric apparent to mean place
+*
+* The mean coordinate system is the post IAU 1976 system,
+* loosely called FK5.
+*
+* Use of this routine is appropriate when efficiency is important
+* and where many star positions are all to be transformed for
+* one epoch and equinox. The star-independent parameters can be
+* obtained by calling the slMAPA routine.
+*
+* Given:
+* RA d apparent RA (radians)
+* DA d apparent Dec (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) (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:
+* 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)
+*
+* Note:
+*
+* 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.
+*
+* Called: slDS2C, slDIMV, slDVDV, slDVN, slDC2S,
+* slDA2P
+*
+* P.T.Wallace Starlink 7 May 2000
+*
+* Copyright (C) 2000 Rutherford Appleton Laboratory
+*
+* License:
+* This program is free software; you can redistribute it and/or modify
+* it under the terms of the GNU General Public License as published by
+* the Free Software Foundation; either version 2 of the License, or
+* (at your option) any later version.
+*
+* This program is distributed in the hope that it will be useful,
+* but WITHOUT ANY WARRANTY; without even the implied warranty of
+* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+* GNU General Public License for more details.
+*
+* You should have received a copy of the GNU General Public License
+* along with this program (see SLA_CONDITIONS); if not, write to the
+* Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+* Boston, MA 02110-1301 USA
+*
+* Copyright (C) 1995 Association of Universities for Research in Astronomy Inc.
+*-
+
+ IMPLICIT NONE
+
+ DOUBLE PRECISION RA,DA,AMPRMS(21),RM,DM
+
+ INTEGER I,J
+
+ DOUBLE PRECISION GR2E,AB1,EHN(3),ABV(3),P3(3),P2(3),
+ : AB1P1,P1DV,P1DVP1,P1(3),W,PDE,PDEP1,P(3)
+
+ DOUBLE PRECISION slDVDV,slDA2P
+
+
+
+* 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
+
+* Apparent RA,Dec to Cartesian
+ CALL slDS2C(RA,DA,P3)
+
+* Precession and nutation
+ CALL slDIMV(AMPRMS(13),P3,P2)
+
+* Aberration
+ AB1P1 = AB1+1D0
+ DO I=1,3
+ P1(I) = P2(I)
+ END DO
+ DO J=1,2
+ P1DV = slDVDV(P1,ABV)
+ P1DVP1 = 1D0+P1DV
+ W = 1D0+P1DV/AB1P1
+ DO I=1,3
+ P1(I) = (P1DVP1*P2(I)-W*ABV(I))/AB1
+ END DO
+ CALL slDVN(P1,P3,W)
+ DO I=1,3
+ P1(I) = P3(I)
+ END DO
+ END DO
+
+* Light deflection
+ DO I=1,3
+ P(I) = P1(I)
+ END DO
+ DO J=1,5
+ PDE = slDVDV(P,EHN)
+ PDEP1 = 1D0+PDE
+ W = PDEP1-GR2E*PDE
+ DO I=1,3
+ P(I) = (PDEP1*P1(I)-GR2E*EHN(I))/W
+ END DO
+ CALL slDVN(P,P2,W)
+ DO I=1,3
+ P(I) = P2(I)
+ END DO
+ END DO
+
+* Mean RA,Dec
+ CALL slDC2S(P,RM,DM)
+ RM = slDA2P(RM)
+
+ END