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SUBROUTINE sla_GALEQ (DL, DB, DR, DD)
*+
* - - - - - -
* G A L E Q
* - - - - - -
*
* Transformation from IAU 1958 galactic coordinates to
* J2000.0 equatorial coordinates (double precision)
*
* Given:
* DL,DB dp galactic longitude and latitude L2,B2
*
* Returned:
* DR,DD dp J2000.0 RA,Dec
*
* (all arguments are radians)
*
* Called:
* sla_DCS2C, sla_DIMXV, sla_DCC2S, sla_DRANRM, sla_DRANGE
*
* Note:
* The equatorial coordinates are J2000.0. Use the routine
* sla_GE50 if conversion to B1950.0 'FK4' coordinates is
* required.
*
* Reference:
* Blaauw et al, Mon.Not.R.Astron.Soc.,121,123 (1960)
*
* P.T.Wallace Starlink 21 September 1998
*
* Copyright (C) 1998 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., 59 Temple Place, Suite 330,
* Boston, MA 02111-1307 USA
*
*-
IMPLICIT NONE
DOUBLE PRECISION DL,DB,DR,DD
DOUBLE PRECISION sla_DRANRM,sla_DRANGE
DOUBLE PRECISION V1(3),V2(3)
*
* L2,B2 system of galactic coordinates
*
* P = 192.25 RA of galactic north pole (mean B1950.0)
* Q = 62.6 inclination of galactic to mean B1950.0 equator
* R = 33 longitude of ascending node
*
* P,Q,R are degrees
*
* Equatorial to galactic rotation matrix (J2000.0), obtained by
* applying the standard FK4 to FK5 transformation, for zero proper
* motion in FK5, to the columns of the B1950 equatorial to
* galactic rotation matrix:
*
DOUBLE PRECISION RMAT(3,3)
DATA RMAT(1,1),RMAT(1,2),RMAT(1,3),
: RMAT(2,1),RMAT(2,2),RMAT(2,3),
: RMAT(3,1),RMAT(3,2),RMAT(3,3)/
: -0.054875539726D0,-0.873437108010D0,-0.483834985808D0,
: +0.494109453312D0,-0.444829589425D0,+0.746982251810D0,
: -0.867666135858D0,-0.198076386122D0,+0.455983795705D0/
* Spherical to Cartesian
CALL sla_DCS2C(DL,DB,V1)
* Galactic to equatorial
CALL sla_DIMXV(RMAT,V1,V2)
* Cartesian to spherical
CALL sla_DCC2S(V2,DR,DD)
* Express in conventional ranges
DR=sla_DRANRM(DR)
DD=sla_DRANGE(DD)
END
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