source: trunk/FACT++/sofa/src/bi00.c@ 18365

Last change on this file since 18365 was 18346, checked in by tbretz, 10 years ago
File size: 6.5 KB
Line 
1#include "sofa.h"
2
3void iauBi00(double *dpsibi, double *depsbi, double *dra)
4/*
5** - - - - - - - -
6** i a u B i 0 0
7** - - - - - - - -
8**
9** Frame bias components of IAU 2000 precession-nutation models (part
10** of MHB2000 with additions).
11**
12** This function is part of the International Astronomical Union's
13** SOFA (Standards Of Fundamental Astronomy) software collection.
14**
15** Status: canonical model.
16**
17** Returned:
18** dpsibi,depsbi double longitude and obliquity corrections
19** dra double the ICRS RA of the J2000.0 mean equinox
20**
21** Notes:
22**
23** 1) The frame bias corrections in longitude and obliquity (radians)
24** are required in order to correct for the offset between the GCRS
25** pole and the mean J2000.0 pole. They define, with respect to the
26** GCRS frame, a J2000.0 mean pole that is consistent with the rest
27** of the IAU 2000A precession-nutation model.
28**
29** 2) In addition to the displacement of the pole, the complete
30** description of the frame bias requires also an offset in right
31** ascension. This is not part of the IAU 2000A model, and is from
32** Chapront et al. (2002). It is returned in radians.
33**
34** 3) This is a supplemented implementation of one aspect of the IAU
35** 2000A nutation model, formally adopted by the IAU General
36** Assembly in 2000, namely MHB2000 (Mathews et al. 2002).
37**
38** References:
39**
40** Chapront, J., Chapront-Touze, M. & Francou, G., Astron.
41** Astrophys., 387, 700, 2002.
42**
43** Mathews, P.M., Herring, T.A., Buffet, B.A., "Modeling of nutation
44** and precession New nutation series for nonrigid Earth and
45** insights into the Earth's interior", J.Geophys.Res., 107, B4,
46** 2002. The MHB2000 code itself was obtained on 9th September 2002
47** from ftp://maia.usno.navy.mil/conv2000/chapter5/IAU2000A.
48**
49** This revision: 2013 June 18
50**
51** SOFA release 2015-02-09
52**
53** Copyright (C) 2015 IAU SOFA Board. See notes at end.
54*/
55{
56/* The frame bias corrections in longitude and obliquity */
57 const double DPBIAS = -0.041775 * DAS2R,
58 DEBIAS = -0.0068192 * DAS2R;
59
60/* The ICRS RA of the J2000.0 equinox (Chapront et al., 2002) */
61 const double DRA0 = -0.0146 * DAS2R;
62
63/* Return the results (which are fixed). */
64 *dpsibi = DPBIAS;
65 *depsbi = DEBIAS;
66 *dra = DRA0;
67
68 return;
69
70/*----------------------------------------------------------------------
71**
72** Copyright (C) 2015
73** Standards Of Fundamental Astronomy Board
74** of the International Astronomical Union.
75**
76** =====================
77** SOFA Software License
78** =====================
79**
80** NOTICE TO USER:
81**
82** BY USING THIS SOFTWARE YOU ACCEPT THE FOLLOWING SIX TERMS AND
83** CONDITIONS WHICH APPLY TO ITS USE.
84**
85** 1. The Software is owned by the IAU SOFA Board ("SOFA").
86**
87** 2. Permission is granted to anyone to use the SOFA software for any
88** purpose, including commercial applications, free of charge and
89** without payment of royalties, subject to the conditions and
90** restrictions listed below.
91**
92** 3. You (the user) may copy and distribute SOFA source code to others,
93** and use and adapt its code and algorithms in your own software,
94** on a world-wide, royalty-free basis. That portion of your
95** distribution that does not consist of intact and unchanged copies
96** of SOFA source code files is a "derived work" that must comply
97** with the following requirements:
98**
99** a) Your work shall be marked or carry a statement that it
100** (i) uses routines and computations derived by you from
101** software provided by SOFA under license to you; and
102** (ii) does not itself constitute software provided by and/or
103** endorsed by SOFA.
104**
105** b) The source code of your derived work must contain descriptions
106** of how the derived work is based upon, contains and/or differs
107** from the original SOFA software.
108**
109** c) The names of all routines in your derived work shall not
110** include the prefix "iau" or "sofa" or trivial modifications
111** thereof such as changes of case.
112**
113** d) The origin of the SOFA components of your derived work must
114** not be misrepresented; you must not claim that you wrote the
115** original software, nor file a patent application for SOFA
116** software or algorithms embedded in the SOFA software.
117**
118** e) These requirements must be reproduced intact in any source
119** distribution and shall apply to anyone to whom you have
120** granted a further right to modify the source code of your
121** derived work.
122**
123** Note that, as originally distributed, the SOFA software is
124** intended to be a definitive implementation of the IAU standards,
125** and consequently third-party modifications are discouraged. All
126** variations, no matter how minor, must be explicitly marked as
127** such, as explained above.
128**
129** 4. You shall not cause the SOFA software to be brought into
130** disrepute, either by misuse, or use for inappropriate tasks, or
131** by inappropriate modification.
132**
133** 5. The SOFA software is provided "as is" and SOFA makes no warranty
134** as to its use or performance. SOFA does not and cannot warrant
135** the performance or results which the user may obtain by using the
136** SOFA software. SOFA makes no warranties, express or implied, as
137** to non-infringement of third party rights, merchantability, or
138** fitness for any particular purpose. In no event will SOFA be
139** liable to the user for any consequential, incidental, or special
140** damages, including any lost profits or lost savings, even if a
141** SOFA representative has been advised of such damages, or for any
142** claim by any third party.
143**
144** 6. The provision of any version of the SOFA software under the terms
145** and conditions specified herein does not imply that future
146** versions will also be made available under the same terms and
147** conditions.
148*
149** In any published work or commercial product which uses the SOFA
150** software directly, acknowledgement (see www.iausofa.org) is
151** appreciated.
152**
153** Correspondence concerning SOFA software should be addressed as
154** follows:
155**
156** By email: sofa@ukho.gov.uk
157** By post: IAU SOFA Center
158** HM Nautical Almanac Office
159** UK Hydrographic Office
160** Admiralty Way, Taunton
161** Somerset, TA1 2DN
162** United Kingdom
163**
164**--------------------------------------------------------------------*/
165}
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