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slalib/galeq.f

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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