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108 lines
2.9 KiB
Fortran
108 lines
2.9 KiB
Fortran
SUBROUTINE sla_EG50 (DR, DD, DL, DB)
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*+
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* - - - - -
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* E G 5 0
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* - - - - -
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*
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* Transformation from B1950.0 'FK4' equatorial coordinates to
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* IAU 1958 galactic coordinates (double precision)
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*
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* Given:
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* DR,DD dp B1950.0 'FK4' RA,Dec
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*
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* Returned:
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* DL,DB dp galactic longitude and latitude L2,B2
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*
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* (all arguments are radians)
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*
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* Called:
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* sla_DCS2C, sla_DMXV, sla_DCC2S, sla_SUBET, sla_DRANRM, sla_DRANGE
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*
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* Note:
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* The equatorial coordinates are B1950.0 'FK4'. Use the
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* routine sla_EQGAL if conversion from J2000.0 coordinates
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* is required.
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*
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* Reference:
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* Blaauw et al, Mon.Not.R.Astron.Soc.,121,123 (1960)
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*
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* P.T.Wallace Starlink 5 September 1993
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*
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* Copyright (C) 1995 Rutherford Appleton Laboratory
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*
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* License:
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program (see SLA_CONDITIONS); if not, write to the
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* Free Software Foundation, Inc., 59 Temple Place, Suite 330,
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* Boston, MA 02111-1307 USA
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*
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*-
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IMPLICIT NONE
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DOUBLE PRECISION DR,DD,DL,DB
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DOUBLE PRECISION sla_DRANRM,sla_DRANGE
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DOUBLE PRECISION V1(3),V2(3),R,D
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*
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* L2,B2 system of galactic coordinates
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*
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* P = 192.25 RA of galactic north pole (mean B1950.0)
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* Q = 62.6 inclination of galactic to mean B1950.0 equator
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* R = 33 longitude of ascending node
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*
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* P,Q,R are degrees
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*
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*
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* Equatorial to galactic rotation matrix
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*
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* The Euler angles are P, Q, 90-R, about the z then y then
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* z axes.
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*
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* +CP.CQ.SR-SP.CR +SP.CQ.SR+CP.CR -SQ.SR
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*
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* -CP.CQ.CR-SP.SR -SP.CQ.CR+CP.SR +SQ.CR
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*
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* +CP.SQ +SP.SQ +CQ
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*
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DOUBLE PRECISION RMAT(3,3)
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DATA RMAT(1,1),RMAT(1,2),RMAT(1,3),
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: RMAT(2,1),RMAT(2,2),RMAT(2,3),
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: RMAT(3,1),RMAT(3,2),RMAT(3,3) /
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: -0.066988739415D0,-0.872755765852D0,-0.483538914632D0,
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: +0.492728466075D0,-0.450346958020D0,+0.744584633283D0,
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: -0.867600811151D0,-0.188374601723D0,+0.460199784784D0 /
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* Remove E-terms
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CALL sla_SUBET(DR,DD,1950D0,R,D)
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* Spherical to Cartesian
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CALL sla_DCS2C(R,D,V1)
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* Rotate to galactic
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CALL sla_DMXV(RMAT,V1,V2)
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* Cartesian to spherical
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CALL sla_DCC2S(V2,DL,DB)
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* Express angles in conventional ranges
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DL=sla_DRANRM(DL)
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DB=sla_DRANGE(DB)
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END
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