source: branches/FACT++_lidctrl_usb/erfa/src/hfk5z.c@ 19675

Last change on this file since 19675 was 18711, checked in by tbretz, 9 years ago
Updated to ERFA 1.3.0 (no relevant code change except the leap second at the beginning of 2017)
File size: 7.1 KB
Line 
1#include "erfa.h"
2
3void eraHfk5z(double rh, double dh, double date1, double date2,
4 double *r5, double *d5, double *dr5, double *dd5)
5/*
6** - - - - - - - - -
7** e r a H f k 5 z
8** - - - - - - - - -
9**
10** Transform a Hipparcos star position into FK5 J2000.0, assuming
11** zero Hipparcos proper motion.
12**
13** Given:
14** rh double Hipparcos RA (radians)
15** dh double Hipparcos Dec (radians)
16** date1,date2 double TDB date (Note 1)
17**
18** Returned (all FK5, equinox J2000.0, date date1+date2):
19** r5 double RA (radians)
20** d5 double Dec (radians)
21** dr5 double FK5 RA proper motion (rad/year, Note 4)
22** dd5 double Dec proper motion (rad/year, Note 4)
23**
24** Notes:
25**
26** 1) The TT date date1+date2 is a Julian Date, apportioned in any
27** convenient way between the two arguments. For example,
28** JD(TT)=2450123.7 could be expressed in any of these ways,
29** among others:
30**
31** date1 date2
32**
33** 2450123.7 0.0 (JD method)
34** 2451545.0 -1421.3 (J2000 method)
35** 2400000.5 50123.2 (MJD method)
36** 2450123.5 0.2 (date & time method)
37**
38** The JD method is the most natural and convenient to use in
39** cases where the loss of several decimal digits of resolution
40** is acceptable. The J2000 method is best matched to the way
41** the argument is handled internally and will deliver the
42** optimum resolution. The MJD method and the date & time methods
43** are both good compromises between resolution and convenience.
44**
45** 2) The proper motion in RA is dRA/dt rather than cos(Dec)*dRA/dt.
46**
47** 3) The FK5 to Hipparcos transformation is modeled as a pure rotation
48** and spin; zonal errors in the FK5 catalogue are not taken into
49** account.
50**
51** 4) It was the intention that Hipparcos should be a close
52** approximation to an inertial frame, so that distant objects have
53** zero proper motion; such objects have (in general) non-zero
54** proper motion in FK5, and this function returns those fictitious
55** proper motions.
56**
57** 5) The position returned by this function is in the FK5 J2000.0
58** reference system but at date date1+date2.
59**
60** 6) See also eraFk52h, eraH2fk5, eraFk5zhz.
61**
62** Called:
63** eraS2c spherical coordinates to unit vector
64** eraFk5hip FK5 to Hipparcos rotation and spin
65** eraRxp product of r-matrix and p-vector
66** eraSxp multiply p-vector by scalar
67** eraRxr product of two r-matrices
68** eraTrxp product of transpose of r-matrix and p-vector
69** eraPxp vector product of two p-vectors
70** eraPv2s pv-vector to spherical
71** eraAnp normalize angle into range 0 to 2pi
72**
73** Reference:
74**
75** F.Mignard & M.Froeschle, 2000, Astron.Astrophys. 354, 732-739.
76**
77** Copyright (C) 2013-2016, NumFOCUS Foundation.
78** Derived, with permission, from the SOFA library. See notes at end of file.
79*/
80{
81 double t, ph[3], r5h[3][3], s5h[3], sh[3], vst[3],
82 rst[3][3], r5ht[3][3], pv5e[2][3], vv[3],
83 w, r, v;
84
85
86/* Time interval from fundamental epoch J2000.0 to given date (JY). */
87 t = ((date1 - ERFA_DJ00) + date2) / ERFA_DJY;
88
89/* Hipparcos barycentric position vector (normalized). */
90 eraS2c(rh, dh, ph);
91
92/* FK5 to Hipparcos orientation matrix and spin vector. */
93 eraFk5hip(r5h, s5h);
94
95/* Rotate the spin into the Hipparcos system. */
96 eraRxp(r5h, s5h, sh);
97
98/* Accumulated Hipparcos wrt FK5 spin over that interval. */
99 eraSxp(t, s5h, vst);
100
101/* Express the accumulated spin as a rotation matrix. */
102 eraRv2m(vst, rst);
103
104/* Rotation matrix: accumulated spin, then FK5 to Hipparcos. */
105 eraRxr(r5h, rst, r5ht);
106
107/* De-orient & de-spin the Hipparcos position into FK5 J2000.0. */
108 eraTrxp(r5ht, ph, pv5e[0]);
109
110/* Apply spin to the position giving a space motion. */
111 eraPxp(sh, ph, vv);
112
113/* De-orient & de-spin the Hipparcos space motion into FK5 J2000.0. */
114 eraTrxp(r5ht, vv, pv5e[1]);
115
116/* FK5 position/velocity pv-vector to spherical. */
117 eraPv2s(pv5e, &w, d5, &r, dr5, dd5, &v);
118 *r5 = eraAnp(w);
119
120 return;
121
122}
123/*----------------------------------------------------------------------
124**
125**
126** Copyright (C) 2013-2016, NumFOCUS Foundation.
127** All rights reserved.
128**
129** This library is derived, with permission, from the International
130** Astronomical Union's "Standards of Fundamental Astronomy" library,
131** available from http://www.iausofa.org.
132**
133** The ERFA version is intended to retain identical functionality to
134** the SOFA library, but made distinct through different function and
135** file names, as set out in the SOFA license conditions. The SOFA
136** original has a role as a reference standard for the IAU and IERS,
137** and consequently redistribution is permitted only in its unaltered
138** state. The ERFA version is not subject to this restriction and
139** therefore can be included in distributions which do not support the
140** concept of "read only" software.
141**
142** Although the intent is to replicate the SOFA API (other than
143** replacement of prefix names) and results (with the exception of
144** bugs; any that are discovered will be fixed), SOFA is not
145** responsible for any errors found in this version of the library.
146**
147** If you wish to acknowledge the SOFA heritage, please acknowledge
148** that you are using a library derived from SOFA, rather than SOFA
149** itself.
150**
151**
152** TERMS AND CONDITIONS
153**
154** Redistribution and use in source and binary forms, with or without
155** modification, are permitted provided that the following conditions
156** are met:
157**
158** 1 Redistributions of source code must retain the above copyright
159** notice, this list of conditions and the following disclaimer.
160**
161** 2 Redistributions in binary form must reproduce the above copyright
162** notice, this list of conditions and the following disclaimer in
163** the documentation and/or other materials provided with the
164** distribution.
165**
166** 3 Neither the name of the Standards Of Fundamental Astronomy Board,
167** the International Astronomical Union nor the names of its
168** contributors may be used to endorse or promote products derived
169** from this software without specific prior written permission.
170**
171** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
172** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
173** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
174** FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
175** COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
176** INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
177** BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
178** LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
179** CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
180** LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
181** ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
182** POSSIBILITY OF SUCH DAMAGE.
183**
184*/
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