source: branches/FACT++_part_filenames/erfa/src/bi00.c@ 20115

Last change on this file since 20115 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: 5.1 KB
Line 
1#include "erfa.h"
2
3void eraBi00(double *dpsibi, double *depsbi, double *dra)
4/*
5** - - - - - - - -
6** e r a B i 0 0
7** - - - - - - - -
8**
9** Frame bias components of IAU 2000 precession-nutation models (part
10** of MHB2000 with additions).
11**
12** Returned:
13** dpsibi,depsbi double longitude and obliquity corrections
14** dra double the ICRS RA of the J2000.0 mean equinox
15**
16** Notes:
17**
18** 1) The frame bias corrections in longitude and obliquity (radians)
19** are required in order to correct for the offset between the GCRS
20** pole and the mean J2000.0 pole. They define, with respect to the
21** GCRS frame, a J2000.0 mean pole that is consistent with the rest
22** of the IAU 2000A precession-nutation model.
23**
24** 2) In addition to the displacement of the pole, the complete
25** description of the frame bias requires also an offset in right
26** ascension. This is not part of the IAU 2000A model, and is from
27** Chapront et al. (2002). It is returned in radians.
28**
29** 3) This is a supplemented implementation of one aspect of the IAU
30** 2000A nutation model, formally adopted by the IAU General
31** Assembly in 2000, namely MHB2000 (Mathews et al. 2002).
32**
33** References:
34**
35** Chapront, J., Chapront-Touze, M. & Francou, G., Astron.
36** Astrophys., 387, 700, 2002.
37**
38** Mathews, P.M., Herring, T.A., Buffet, B.A., "Modeling of nutation
39** and precession New nutation series for nonrigid Earth and
40** insights into the Earth's interior", J.Geophys.Res., 107, B4,
41** 2002. The MHB2000 code itself was obtained on 9th September 2002
42** from ftp://maia.usno.navy.mil/conv2000/chapter5/IAU2000A.
43**
44** Copyright (C) 2013-2016, NumFOCUS Foundation.
45** Derived, with permission, from the SOFA library. See notes at end of file.
46*/
47{
48/* The frame bias corrections in longitude and obliquity */
49 const double DPBIAS = -0.041775 * ERFA_DAS2R,
50 DEBIAS = -0.0068192 * ERFA_DAS2R;
51
52/* The ICRS RA of the J2000.0 equinox (Chapront et al., 2002) */
53 const double DRA0 = -0.0146 * ERFA_DAS2R;
54
55
56/* Return the results (which are fixed). */
57 *dpsibi = DPBIAS;
58 *depsbi = DEBIAS;
59 *dra = DRA0;
60
61 return;
62
63}
64/*----------------------------------------------------------------------
65**
66**
67** Copyright (C) 2013-2016, NumFOCUS Foundation.
68** All rights reserved.
69**
70** This library is derived, with permission, from the International
71** Astronomical Union's "Standards of Fundamental Astronomy" library,
72** available from http://www.iausofa.org.
73**
74** The ERFA version is intended to retain identical functionality to
75** the SOFA library, but made distinct through different function and
76** file names, as set out in the SOFA license conditions. The SOFA
77** original has a role as a reference standard for the IAU and IERS,
78** and consequently redistribution is permitted only in its unaltered
79** state. The ERFA version is not subject to this restriction and
80** therefore can be included in distributions which do not support the
81** concept of "read only" software.
82**
83** Although the intent is to replicate the SOFA API (other than
84** replacement of prefix names) and results (with the exception of
85** bugs; any that are discovered will be fixed), SOFA is not
86** responsible for any errors found in this version of the library.
87**
88** If you wish to acknowledge the SOFA heritage, please acknowledge
89** that you are using a library derived from SOFA, rather than SOFA
90** itself.
91**
92**
93** TERMS AND CONDITIONS
94**
95** Redistribution and use in source and binary forms, with or without
96** modification, are permitted provided that the following conditions
97** are met:
98**
99** 1 Redistributions of source code must retain the above copyright
100** notice, this list of conditions and the following disclaimer.
101**
102** 2 Redistributions in binary form must reproduce the above copyright
103** notice, this list of conditions and the following disclaimer in
104** the documentation and/or other materials provided with the
105** distribution.
106**
107** 3 Neither the name of the Standards Of Fundamental Astronomy Board,
108** the International Astronomical Union nor the names of its
109** contributors may be used to endorse or promote products derived
110** from this software without specific prior written permission.
111**
112** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
113** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
114** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
115** FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
116** COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
117** INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
118** BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
119** LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
120** CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
121** LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
122** ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
123** POSSIBILITY OF SUCH DAMAGE.
124**
125*/
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