1 /*
2 *+
3 * Name:
4 * palGe50
5
6 * Purpose:
7 * Transform Galactic Coordinate to B1950 FK4
8
9 * Language:
10 * Starlink ANSI C
11
12 * Type of Module:
13 * Library routine
14
15 * Invocation:
16 * palGe50( double dl, double db, double *dr, double *dd );
17
18 * Arguments:
19 * dl = double (Given)
20 * Galactic longitude (radians)
21 * db = double (Given)
22 * Galactic latitude (radians)
23 * dr = double * (Returned)
24 * B9150.0 FK4 RA.
25 * dd = double * (Returned)
26 * B1950.0 FK4 Dec.
27
28 * Description:
29 * Transformation from IAU 1958 galactic coordinates to
30 * B1950.0 'FK4' equatorial coordinates.
31
32 * Authors:
33 * PTW: Patrick T. Wallace
34 * TIMJ: Tim Jenness (JAC, Hawaii)
35 * {enter_new_authors_here}
36
37 * Notes:
38 * - The equatorial coordinates are B1950.0 'FK4'. Use the routine
39 * palGaleq if conversion to J2000.0 coordinates is required.
40
41 * See Also:
42 * - Blaauw et al, Mon.Not.R.Astron.Soc.,121,123 (1960)
43
44 * History:
45 * 2012-03-23 (TIMJ):
46 * Initial version
47 * Adapted with permission from the Fortran SLALIB library.
48 * {enter_further_changes_here}
49
50 * Copyright:
51 * Copyright (C) 1995 Rutherford Appleton Laboratory
52 * Copyright (C) 2012 Science and Technology Facilities Council.
53 * All Rights Reserved.
54
55 * Licence:
56 * This program is free software; you can redistribute it and/or
57 * modify it under the terms of the GNU General Public License as
58 * published by the Free Software Foundation; either version 3 of
59 * the License, or (at your option) any later version.
60 *
61 * This program is distributed in the hope that it will be
62 * useful, but WITHOUT ANY WARRANTY; without even the implied
63 * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
64 * PURPOSE. See the GNU General Public License for more details.
65 *
66 * You should have received a copy of the GNU General Public License
67 * along with this program; if not, write to the Free Software
68 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
69 * MA 02110-1301, USA.
70
71 * Bugs:
72 * {note_any_bugs_here}
73 *-
74 */
75
76 #include "pal.h"
77 #include "pal1sofa.h"
78
palGe50(double dl,double db,double * dr,double * dd)79 void palGe50 ( double dl, double db, double * dr, double * dd ) {
80
81 /*
82 * L2,B2 system of galactic coordinates
83 *
84 * P = 192.25 RA of galactic north pole (mean B1950.0)
85 * Q = 62.6 inclination of galactic to mean B1950.0 equator
86 * R = 33 longitude of ascending node
87 *
88 * P,Q,R are degrees
89 *
90 *
91 * Equatorial to galactic rotation matrix
92 *
93 * The Euler angles are P, Q, 90-R, about the z then y then
94 * z axes.
95 *
96 * +CP.CQ.SR-SP.CR +SP.CQ.SR+CP.CR -SQ.SR
97 *
98 * -CP.CQ.CR-SP.SR -SP.CQ.CR+CP.SR +SQ.CR
99 *
100 * +CP.SQ +SP.SQ +CQ
101 *
102 */
103
104 double rmat[3][3] = {
105 { -0.066988739415,-0.872755765852,-0.483538914632 },
106 { +0.492728466075,-0.450346958020,+0.744584633283 },
107 { -0.867600811151,-0.188374601723,+0.460199784784 }
108 };
109
110 double v1[3], v2[3], r, d, re, de;
111
112 /* Spherical to cartesian */
113 eraS2c( dl, db, v1 );
114
115 /* Rotate to mean B1950.0 */
116 eraTrxp( rmat, v1, v2 );
117
118 /* Cartesian to spherical */
119 eraC2s( v2, &r, &d );
120
121 /* Introduce E-terms */
122 palAddet( r, d, 1950.0, &re, &de );
123
124 /* Express in conventional ranges */
125 *dr = eraAnp( re );
126 *dd = eraAnpm( de );
127
128 }
129