FACT++  1.0
fk5hip.c
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1 #include "erfa.h"
2 
3 void eraFk5hip(double r5h[3][3], double s5h[3])
4 /*
5 ** - - - - - - - - - -
6 ** e r a F k 5 h i p
7 ** - - - - - - - - - -
8 **
9 ** FK5 to Hipparcos rotation and spin.
10 **
11 ** Returned:
12 ** r5h double[3][3] r-matrix: FK5 rotation wrt Hipparcos (Note 2)
13 ** s5h double[3] r-vector: FK5 spin wrt Hipparcos (Note 3)
14 **
15 ** Notes:
16 **
17 ** 1) This function models the FK5 to Hipparcos transformation as a
18 ** pure rotation and spin; zonal errors in the FK5 catalogue are
19 ** not taken into account.
20 **
21 ** 2) The r-matrix r5h operates in the sense:
22 **
23 ** P_Hipparcos = r5h x P_FK5
24 **
25 ** where P_FK5 is a p-vector in the FK5 frame, and P_Hipparcos is
26 ** the equivalent Hipparcos p-vector.
27 **
28 ** 3) The r-vector s5h represents the time derivative of the FK5 to
29 ** Hipparcos rotation. The units are radians per year (Julian,
30 ** TDB).
31 **
32 ** Called:
33 ** eraRv2m r-vector to r-matrix
34 **
35 ** Reference:
36 **
37 ** F.Mignard & M.Froeschle, Astron. Astrophys. 354, 732-739 (2000).
38 **
39 ** Copyright (C) 2013-2015, NumFOCUS Foundation.
40 ** Derived, with permission, from the SOFA library. See notes at end of file.
41 */
42 {
43  double v[3];
44 
45 /* FK5 wrt Hipparcos orientation and spin (radians, radians/year) */
46  double epx, epy, epz;
47  double omx, omy, omz;
48 
49  epx = -19.9e-3 * ERFA_DAS2R;
50  epy = -9.1e-3 * ERFA_DAS2R;
51  epz = 22.9e-3 * ERFA_DAS2R;
52 
53  omx = -0.30e-3 * ERFA_DAS2R;
54  omy = 0.60e-3 * ERFA_DAS2R;
55  omz = 0.70e-3 * ERFA_DAS2R;
56 
57 /* FK5 to Hipparcos orientation expressed as an r-vector. */
58  v[0] = epx;
59  v[1] = epy;
60  v[2] = epz;
61 
62 /* Re-express as an r-matrix. */
63  eraRv2m(v, r5h);
64 
65 /* Hipparcos wrt FK5 spin expressed as an r-vector. */
66  s5h[0] = omx;
67  s5h[1] = omy;
68  s5h[2] = omz;
69 
70  return;
71 
72 }
73 /*----------------------------------------------------------------------
74 **
75 **
76 ** Copyright (C) 2013-2015, NumFOCUS Foundation.
77 ** All rights reserved.
78 **
79 ** This library is derived, with permission, from the International
80 ** Astronomical Union's "Standards of Fundamental Astronomy" library,
81 ** available from http://www.iausofa.org.
82 **
83 ** The ERFA version is intended to retain identical functionality to
84 ** the SOFA library, but made distinct through different function and
85 ** file names, as set out in the SOFA license conditions. The SOFA
86 ** original has a role as a reference standard for the IAU and IERS,
87 ** and consequently redistribution is permitted only in its unaltered
88 ** state. The ERFA version is not subject to this restriction and
89 ** therefore can be included in distributions which do not support the
90 ** concept of "read only" software.
91 **
92 ** Although the intent is to replicate the SOFA API (other than
93 ** replacement of prefix names) and results (with the exception of
94 ** bugs; any that are discovered will be fixed), SOFA is not
95 ** responsible for any errors found in this version of the library.
96 **
97 ** If you wish to acknowledge the SOFA heritage, please acknowledge
98 ** that you are using a library derived from SOFA, rather than SOFA
99 ** itself.
100 **
101 **
102 ** TERMS AND CONDITIONS
103 **
104 ** Redistribution and use in source and binary forms, with or without
105 ** modification, are permitted provided that the following conditions
106 ** are met:
107 **
108 ** 1 Redistributions of source code must retain the above copyright
109 ** notice, this list of conditions and the following disclaimer.
110 **
111 ** 2 Redistributions in binary form must reproduce the above copyright
112 ** notice, this list of conditions and the following disclaimer in
113 ** the documentation and/or other materials provided with the
114 ** distribution.
115 **
116 ** 3 Neither the name of the Standards Of Fundamental Astronomy Board,
117 ** the International Astronomical Union nor the names of its
118 ** contributors may be used to endorse or promote products derived
119 ** from this software without specific prior written permission.
120 **
121 ** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
122 ** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
123 ** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
124 ** FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
125 ** COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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127 ** BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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132 ** POSSIBILITY OF SUCH DAMAGE.
133 **
134 */
ERFA_DAS2R
#define ERFA_DAS2R
Definition: erfam.h:60
eraRv2m
void eraRv2m(double w[3], double r[3][3])
Definition: rv2m.c:3
eraFk5hip
void eraFk5hip(double r5h[3][3], double s5h[3])
Definition: fk5hip.c:3