source: trunk/FACT++/pal/palAddet.c@ 20004

Last change on this file since 20004 was 18347, checked in by tbretz, 9 years ago
File size: 3.0 KB
Line 
1/*
2*+
3* Name:
4* palAddet
5
6* Purpose:
7* Add the E-terms to a pre IAU 1976 mean place
8
9* Language:
10* Starlink ANSI C
11
12* Type of Module:
13* Library routine
14
15* Invocation:
16* void palAddet ( double rm, double dm, double eq,
17* double *rc, double *dc );
18
19* Arguments:
20* rm = double (Given)
21* RA without E-terms (radians)
22* dm = double (Given)
23* Dec without E-terms (radians)
24* eq = double (Given)
25* Besselian epoch of mean equator and equinox
26* rc = double * (Returned)
27* RA with E-terms included (radians)
28* dc = double * (Returned)
29* Dec with E-terms included (radians)
30
31* Description:
32* Add the E-terms (elliptic component of annual aberration)
33* to a pre IAU 1976 mean place to conform to the old
34* catalogue convention.
35
36* Authors:
37* PTW: Pat Wallace (STFC)
38* TIMJ: Tim Jenness (JAC, Hawaii)
39* {enter_new_authors_here}
40
41* Notes:
42* Most star positions from pre-1984 optical catalogues (or
43* derived from astrometry using such stars) embody the
44* E-terms. If it is necessary to convert a formal mean
45* place (for example a pulsar timing position) to one
46* consistent with such a star catalogue, then the RA,Dec
47* should be adjusted using this routine.
48
49* See Also:
50* Explanatory Supplement to the Astronomical Ephemeris,
51* section 2D, page 48.
52
53* History:
54* 2012-02-12(TIMJ):
55* Initial version with documentation taken from Fortran SLA
56* Adapted with permission from the Fortran SLALIB library.
57* {enter_further_changes_here}
58
59* Copyright:
60* Copyright (C) 1999 Rutherford Appleton Laboratory
61* Copyright (C) 2012 Science and Technology Facilities Council.
62* All Rights Reserved.
63
64* Licence:
65* This program is free software: you can redistribute it and/or
66* modify it under the terms of the GNU Lesser General Public
67* License as published by the Free Software Foundation, either
68* version 3 of the License, or (at your option) any later
69* version.
70*
71* This program is distributed in the hope that it will be useful,
72* but WITHOUT ANY WARRANTY; without even the implied warranty of
73* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
74* GNU Lesser General Public License for more details.
75*
76* You should have received a copy of the GNU Lesser General
77* License along with this program. If not, see
78* <http://www.gnu.org/licenses/>.
79
80* Bugs:
81* {note_any_bugs_here}
82*-
83*/
84
85#include "pal.h"
86#include "pal1sofa.h"
87
88void palAddet ( double rm, double dm, double eq, double *rc, double *dc ) {
89 double a[3]; /* The E-terms */
90 double v[3];
91 int i;
92
93 /* Note the preference for IAU routines */
94
95 /* Retrieve the E-terms */
96 palEtrms( eq, a );
97
98 /* Spherical to Cartesian */
99 eraS2c( rm, dm, v );
100
101 /* Include the E-terms */
102 for (i=0; i<3; i++) {
103 v[i] += a[i];
104 }
105
106 /* Cartesian to spherical */
107 eraC2s( v, rc, dc );
108
109 /* Bring RA into conventional range */
110 *rc = eraAnp( *rc );
111
112}
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