source: trunk/FACT++/erfa/src/bp00.c@ 20000

Last change on this file since 20000 was 18921, checked in by tbretz, 8 years ago
Updated to ERFA 1.4.0
File size: 6.9 KB
Line 
1#include "erfa.h"
2
3void eraBp00(double date1, double date2,
4 double rb[3][3], double rp[3][3], double rbp[3][3])
5/*
6** - - - - - - - -
7** e r a B p 0 0
8** - - - - - - - -
9**
10** Frame bias and precession, IAU 2000.
11**
12** Given:
13** date1,date2 double TT as a 2-part Julian Date (Note 1)
14**
15** Returned:
16** rb double[3][3] frame bias matrix (Note 2)
17** rp double[3][3] precession matrix (Note 3)
18** rbp double[3][3] bias-precession matrix (Note 4)
19**
20** Notes:
21**
22** 1) The TT date date1+date2 is a Julian Date, apportioned in any
23** convenient way between the two arguments. For example,
24** JD(TT)=2450123.7 could be expressed in any of these ways,
25** among others:
26**
27** date1 date2
28**
29** 2450123.7 0.0 (JD method)
30** 2451545.0 -1421.3 (J2000 method)
31** 2400000.5 50123.2 (MJD method)
32** 2450123.5 0.2 (date & time method)
33**
34** The JD method is the most natural and convenient to use in
35** cases where the loss of several decimal digits of resolution
36** is acceptable. The J2000 method is best matched to the way
37** the argument is handled internally and will deliver the
38** optimum resolution. The MJD method and the date & time methods
39** are both good compromises between resolution and convenience.
40**
41** 2) The matrix rb transforms vectors from GCRS to mean J2000.0 by
42** applying frame bias.
43**
44** 3) The matrix rp transforms vectors from J2000.0 mean equator and
45** equinox to mean equator and equinox of date by applying
46** precession.
47**
48** 4) The matrix rbp transforms vectors from GCRS to mean equator and
49** equinox of date by applying frame bias then precession. It is
50** the product rp x rb.
51**
52** 5) It is permissible to re-use the same array in the returned
53** arguments. The arrays are filled in the order given.
54**
55** Called:
56** eraBi00 frame bias components, IAU 2000
57** eraPr00 IAU 2000 precession adjustments
58** eraIr initialize r-matrix to identity
59** eraRx rotate around X-axis
60** eraRy rotate around Y-axis
61** eraRz rotate around Z-axis
62** eraCr copy r-matrix
63** eraRxr product of two r-matrices
64**
65** Reference:
66** "Expressions for the Celestial Intermediate Pole and Celestial
67** Ephemeris Origin consistent with the IAU 2000A precession-
68** nutation model", Astron.Astrophys. 400, 1145-1154 (2003)
69**
70** n.b. The celestial ephemeris origin (CEO) was renamed "celestial
71** intermediate origin" (CIO) by IAU 2006 Resolution 2.
72**
73** Copyright (C) 2013-2017, NumFOCUS Foundation.
74** Derived, with permission, from the SOFA library. See notes at end of file.
75*/
76{
77/* J2000.0 obliquity (Lieske et al. 1977) */
78 const double EPS0 = 84381.448 * ERFA_DAS2R;
79
80 double t, dpsibi, depsbi, dra0, psia77, oma77, chia,
81 dpsipr, depspr, psia, oma, rbw[3][3];
82
83
84/* Interval between fundamental epoch J2000.0 and current date (JC). */
85 t = ((date1 - ERFA_DJ00) + date2) / ERFA_DJC;
86
87/* Frame bias. */
88 eraBi00(&dpsibi, &depsbi, &dra0);
89
90/* Precession angles (Lieske et al. 1977) */
91 psia77 = (5038.7784 + (-1.07259 + (-0.001147) * t) * t) * t * ERFA_DAS2R;
92 oma77 = EPS0 + ((0.05127 + (-0.007726) * t) * t) * t * ERFA_DAS2R;
93 chia = ( 10.5526 + (-2.38064 + (-0.001125) * t) * t) * t * ERFA_DAS2R;
94
95/* Apply IAU 2000 precession corrections. */
96 eraPr00(date1, date2, &dpsipr, &depspr);
97 psia = psia77 + dpsipr;
98 oma = oma77 + depspr;
99
100/* Frame bias matrix: GCRS to J2000.0. */
101 eraIr(rbw);
102 eraRz(dra0, rbw);
103 eraRy(dpsibi*sin(EPS0), rbw);
104 eraRx(-depsbi, rbw);
105 eraCr(rbw, rb);
106
107/* Precession matrix: J2000.0 to mean of date. */
108 eraIr(rp);
109 eraRx(EPS0, rp);
110 eraRz(-psia, rp);
111 eraRx(-oma, rp);
112 eraRz(chia, rp);
113
114/* Bias-precession matrix: GCRS to mean of date. */
115 eraRxr(rp, rbw, rbp);
116
117 return;
118
119}
120/*----------------------------------------------------------------------
121**
122**
123** Copyright (C) 2013-2017, NumFOCUS Foundation.
124** All rights reserved.
125**
126** This library is derived, with permission, from the International
127** Astronomical Union's "Standards of Fundamental Astronomy" library,
128** available from http://www.iausofa.org.
129**
130** The ERFA version is intended to retain identical functionality to
131** the SOFA library, but made distinct through different function and
132** file names, as set out in the SOFA license conditions. The SOFA
133** original has a role as a reference standard for the IAU and IERS,
134** and consequently redistribution is permitted only in its unaltered
135** state. The ERFA version is not subject to this restriction and
136** therefore can be included in distributions which do not support the
137** concept of "read only" software.
138**
139** Although the intent is to replicate the SOFA API (other than
140** replacement of prefix names) and results (with the exception of
141** bugs; any that are discovered will be fixed), SOFA is not
142** responsible for any errors found in this version of the library.
143**
144** If you wish to acknowledge the SOFA heritage, please acknowledge
145** that you are using a library derived from SOFA, rather than SOFA
146** itself.
147**
148**
149** TERMS AND CONDITIONS
150**
151** Redistribution and use in source and binary forms, with or without
152** modification, are permitted provided that the following conditions
153** are met:
154**
155** 1 Redistributions of source code must retain the above copyright
156** notice, this list of conditions and the following disclaimer.
157**
158** 2 Redistributions in binary form must reproduce the above copyright
159** notice, this list of conditions and the following disclaimer in
160** the documentation and/or other materials provided with the
161** distribution.
162**
163** 3 Neither the name of the Standards Of Fundamental Astronomy Board,
164** the International Astronomical Union nor the names of its
165** contributors may be used to endorse or promote products derived
166** from this software without specific prior written permission.
167**
168** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
169** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
170** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
171** FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
172** COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
173** INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
174** BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
175** LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
176** CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
177** LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
178** ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
179** POSSIBILITY OF SUCH DAMAGE.
180**
181*/
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