source: trunk/FACT++/sofa/src/ee00.c@ 18355

Last change on this file since 18355 was 18346, checked in by tbretz, 11 years ago
File size: 6.8 KB
Line 
1#include "sofa.h"
2
3double iauEe00(double date1, double date2, double epsa, double dpsi)
4/*
5** - - - - - - - -
6** i a u E e 0 0
7** - - - - - - - -
8**
9** The equation of the equinoxes, compatible with IAU 2000 resolutions,
10** given the nutation in longitude and the mean obliquity.
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** Given:
18** date1,date2 double TT as a 2-part Julian Date (Note 1)
19** epsa double mean obliquity (Note 2)
20** dpsi double nutation in longitude (Note 3)
21**
22** Returned (function value):
23** double equation of the equinoxes (Note 4)
24**
25** Notes:
26**
27** 1) The TT date date1+date2 is a Julian Date, apportioned in any
28** convenient way between the two arguments. For example,
29** JD(TT)=2450123.7 could be expressed in any of these ways,
30** among others:
31**
32** date1 date2
33**
34** 2450123.7 0.0 (JD method)
35** 2451545.0 -1421.3 (J2000 method)
36** 2400000.5 50123.2 (MJD method)
37** 2450123.5 0.2 (date & time method)
38**
39** The JD method is the most natural and convenient to use in
40** cases where the loss of several decimal digits of resolution
41** is acceptable. The J2000 method is best matched to the way
42** the argument is handled internally and will deliver the
43** optimum resolution. The MJD method and the date & time methods
44** are both good compromises between resolution and convenience.
45**
46** 2) The obliquity, in radians, is mean of date.
47**
48** 3) The result, which is in radians, operates in the following sense:
49**
50** Greenwich apparent ST = GMST + equation of the equinoxes
51**
52** 4) The result is compatible with the IAU 2000 resolutions. For
53** further details, see IERS Conventions 2003 and Capitaine et al.
54** (2002).
55**
56** Called:
57** iauEect00 equation of the equinoxes complementary terms
58**
59** References:
60**
61** Capitaine, N., Wallace, P.T. and McCarthy, D.D., "Expressions to
62** implement the IAU 2000 definition of UT1", Astronomy &
63** Astrophysics, 406, 1135-1149 (2003)
64**
65** McCarthy, D. D., Petit, G. (eds.), IERS Conventions (2003),
66** IERS Technical Note No. 32, BKG (2004)
67**
68** This revision: 2008 May 16
69**
70** SOFA release 2015-02-09
71**
72** Copyright (C) 2015 IAU SOFA Board. See notes at end.
73*/
74{
75 double ee;
76
77/* Equation of the equinoxes. */
78 ee = dpsi * cos(epsa) + iauEect00(date1, date2);
79
80 return ee;
81
82/*----------------------------------------------------------------------
83**
84** Copyright (C) 2015
85** Standards Of Fundamental Astronomy Board
86** of the International Astronomical Union.
87**
88** =====================
89** SOFA Software License
90** =====================
91**
92** NOTICE TO USER:
93**
94** BY USING THIS SOFTWARE YOU ACCEPT THE FOLLOWING SIX TERMS AND
95** CONDITIONS WHICH APPLY TO ITS USE.
96**
97** 1. The Software is owned by the IAU SOFA Board ("SOFA").
98**
99** 2. Permission is granted to anyone to use the SOFA software for any
100** purpose, including commercial applications, free of charge and
101** without payment of royalties, subject to the conditions and
102** restrictions listed below.
103**
104** 3. You (the user) may copy and distribute SOFA source code to others,
105** and use and adapt its code and algorithms in your own software,
106** on a world-wide, royalty-free basis. That portion of your
107** distribution that does not consist of intact and unchanged copies
108** of SOFA source code files is a "derived work" that must comply
109** with the following requirements:
110**
111** a) Your work shall be marked or carry a statement that it
112** (i) uses routines and computations derived by you from
113** software provided by SOFA under license to you; and
114** (ii) does not itself constitute software provided by and/or
115** endorsed by SOFA.
116**
117** b) The source code of your derived work must contain descriptions
118** of how the derived work is based upon, contains and/or differs
119** from the original SOFA software.
120**
121** c) The names of all routines in your derived work shall not
122** include the prefix "iau" or "sofa" or trivial modifications
123** thereof such as changes of case.
124**
125** d) The origin of the SOFA components of your derived work must
126** not be misrepresented; you must not claim that you wrote the
127** original software, nor file a patent application for SOFA
128** software or algorithms embedded in the SOFA software.
129**
130** e) These requirements must be reproduced intact in any source
131** distribution and shall apply to anyone to whom you have
132** granted a further right to modify the source code of your
133** derived work.
134**
135** Note that, as originally distributed, the SOFA software is
136** intended to be a definitive implementation of the IAU standards,
137** and consequently third-party modifications are discouraged. All
138** variations, no matter how minor, must be explicitly marked as
139** such, as explained above.
140**
141** 4. You shall not cause the SOFA software to be brought into
142** disrepute, either by misuse, or use for inappropriate tasks, or
143** by inappropriate modification.
144**
145** 5. The SOFA software is provided "as is" and SOFA makes no warranty
146** as to its use or performance. SOFA does not and cannot warrant
147** the performance or results which the user may obtain by using the
148** SOFA software. SOFA makes no warranties, express or implied, as
149** to non-infringement of third party rights, merchantability, or
150** fitness for any particular purpose. In no event will SOFA be
151** liable to the user for any consequential, incidental, or special
152** damages, including any lost profits or lost savings, even if a
153** SOFA representative has been advised of such damages, or for any
154** claim by any third party.
155**
156** 6. The provision of any version of the SOFA software under the terms
157** and conditions specified herein does not imply that future
158** versions will also be made available under the same terms and
159** conditions.
160*
161** In any published work or commercial product which uses the SOFA
162** software directly, acknowledgement (see www.iausofa.org) is
163** appreciated.
164**
165** Correspondence concerning SOFA software should be addressed as
166** follows:
167**
168** By email: sofa@ukho.gov.uk
169** By post: IAU SOFA Center
170** HM Nautical Almanac Office
171** UK Hydrographic Office
172** Admiralty Way, Taunton
173** Somerset, TA1 2DN
174** United Kingdom
175**
176**--------------------------------------------------------------------*/
177}
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