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/*
*+
* Name:
* palGaleq
* Purpose:
* Convert from galactic to J2000.0 equatorial coordinates
* Language:
* Starlink ANSI C
* Type of Module:
* Library routine
* Invocation:
* void palGaleq ( double dl, double db, double *dr, double *dd );
* Arguments:
* dl = double (Given)
* Galactic longitude (radians).
* db = double (Given)
* Galactic latitude (radians).
* dr = double * (Returned)
* J2000.0 RA (radians)
* dd = double * (Returned)
* J2000.0 Dec (radians)
* Description:
* Transformation from IAU 1958 galactic coordinates to
* J2000.0 equatorial coordinates.
* Authors:
* PTW: Pat Wallace (STFC)
* TIMJ: Tim Jenness (JAC, Hawaii)
* {enter_new_authors_here}
* Notes:
* The equatorial coordinates are J2000.0. Use the routine
* palGe50 if conversion to B1950.0 'FK4' coordinates is
* required.
* See Also:
* Blaauw et al, Mon.Not.R.Astron.Soc.,121,123 (1960)
* History:
* 2012-02-12(TIMJ):
* Initial version with documentation taken from Fortran SLA
* Adapted with permission from the Fortran SLALIB library.
* {enter_further_changes_here}
* Copyright:
* Copyright (C) 1998 Rutherford Appleton Laboratory
* Copyright (C) 2012 Science and Technology Facilities Council.
* All Rights Reserved.
* Licence:
* This program is free software: you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation, either
* version 3 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 Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General
* License along with this program. If not, see
* <http://www.gnu.org/licenses/>.
* Bugs:
* {note_any_bugs_here}
*-
*/
#include "pal.h"
#include "pal1sofa.h"
void palGaleq ( double dl, double db, double *dr, double *dd ) {
double v1[3];
double 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 rmat[3][3] = {
{ -0.054875539726,-0.873437108010,-0.483834985808 },
{ +0.494109453312,-0.444829589425,+0.746982251810 },
{ -0.867666135858,-0.198076386122,+0.455983795705 }
};
/* Spherical to Cartesian */
eraS2c( dl, db, v1 );
/* Galactic to equatorial */
eraTrxp( rmat, v1, v2 );
/* Cartesian to spherical */
eraC2s( v2, dr, dd );
/* Express in conventional ranges */
*dr = eraAnp( *dr );
*dd = eraAnpm( *dd );
}
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