FACT++  1.0
ee00.c
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1 #include "erfa.h"
2 
3 double eraEe00(double date1, double date2, double epsa, double dpsi)
4 /*
5 ** - - - - - - - -
6 ** e r a 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 ** Given:
13 ** date1,date2 double TT as a 2-part Julian Date (Note 1)
14 ** epsa double mean obliquity (Note 2)
15 ** dpsi double nutation in longitude (Note 3)
16 **
17 ** Returned (function value):
18 ** double equation of the equinoxes (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 obliquity, in radians, is mean of date.
42 **
43 ** 3) The result, which is in radians, operates in the following sense:
44 **
45 ** Greenwich apparent ST = GMST + equation of the equinoxes
46 **
47 ** 4) The result is compatible with the IAU 2000 resolutions. For
48 ** further details, see IERS Conventions 2003 and Capitaine et al.
49 ** (2002).
50 **
51 ** Called:
52 ** eraEect00 equation of the equinoxes complementary terms
53 **
54 ** References:
55 **
56 ** Capitaine, N., Wallace, P.T. and McCarthy, D.D., "Expressions to
57 ** implement the IAU 2000 definition of UT1", Astronomy &
58 ** Astrophysics, 406, 1135-1149 (2003)
59 **
60 ** McCarthy, D. D., Petit, G. (eds.), IERS Conventions (2003),
61 ** IERS Technical Note No. 32, BKG (2004)
62 **
63 ** Copyright (C) 2013-2015, NumFOCUS Foundation.
64 ** Derived, with permission, from the SOFA library. See notes at end of file.
65 */
66 {
67  double ee;
68 
69 /* Equation of the equinoxes. */
70  ee = dpsi * cos(epsa) + eraEect00(date1, date2);
71 
72  return ee;
73 
74 }
75 /*----------------------------------------------------------------------
76 **
77 **
78 ** Copyright (C) 2013-2015, NumFOCUS Foundation.
79 ** All rights reserved.
80 **
81 ** This library is derived, with permission, from the International
82 ** Astronomical Union's "Standards of Fundamental Astronomy" library,
83 ** available from http://www.iausofa.org.
84 **
85 ** The ERFA version is intended to retain identical functionality to
86 ** the SOFA library, but made distinct through different function and
87 ** file names, as set out in the SOFA license conditions. The SOFA
88 ** original has a role as a reference standard for the IAU and IERS,
89 ** and consequently redistribution is permitted only in its unaltered
90 ** state. The ERFA version is not subject to this restriction and
91 ** therefore can be included in distributions which do not support the
92 ** concept of "read only" software.
93 **
94 ** Although the intent is to replicate the SOFA API (other than
95 ** replacement of prefix names) and results (with the exception of
96 ** bugs; any that are discovered will be fixed), SOFA is not
97 ** responsible for any errors found in this version of the library.
98 **
99 ** If you wish to acknowledge the SOFA heritage, please acknowledge
100 ** that you are using a library derived from SOFA, rather than SOFA
101 ** itself.
102 **
103 **
104 ** TERMS AND CONDITIONS
105 **
106 ** Redistribution and use in source and binary forms, with or without
107 ** modification, are permitted provided that the following conditions
108 ** are met:
109 **
110 ** 1 Redistributions of source code must retain the above copyright
111 ** notice, this list of conditions and the following disclaimer.
112 **
113 ** 2 Redistributions in binary form must reproduce the above copyright
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116 ** distribution.
117 **
118 ** 3 Neither the name of the Standards Of Fundamental Astronomy Board,
119 ** the International Astronomical Union nor the names of its
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122 **
123 ** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
124 ** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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126 ** FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
127 ** COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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129 ** BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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135 **
136 */
eraEe00
double eraEe00(double date1, double date2, double epsa, double dpsi)
Definition: ee00.c:3
eraEect00
double eraEect00(double date1, double date2)
Definition: eect00.c:3