1 #include "erfa.h"
2
eraC2tpe(double tta,double ttb,double uta,double utb,double dpsi,double deps,double xp,double yp,double rc2t[3][3])3 void eraC2tpe(double tta, double ttb, double uta, double utb,
4 double dpsi, double deps, double xp, double yp,
5 double rc2t[3][3])
6 /*
7 ** - - - - - - - - -
8 ** e r a C 2 t p e
9 ** - - - - - - - - -
10 **
11 ** Form the celestial to terrestrial matrix given the date, the UT1,
12 ** the nutation and the polar motion. IAU 2000.
13 **
14 ** Given:
15 ** tta,ttb double TT as a 2-part Julian Date (Note 1)
16 ** uta,utb double UT1 as a 2-part Julian Date (Note 1)
17 ** dpsi,deps double nutation (Note 2)
18 ** xp,yp double coordinates of the pole (radians, Note 3)
19 **
20 ** Returned:
21 ** rc2t double[3][3] celestial-to-terrestrial matrix (Note 4)
22 **
23 ** Notes:
24 **
25 ** 1) The TT and UT1 dates tta+ttb and uta+utb are Julian Dates,
26 ** apportioned in any convenient way between the arguments uta and
27 ** utb. For example, JD(UT1)=2450123.7 could be expressed in any of
28 ** these ways, among others:
29 **
30 ** uta utb
31 **
32 ** 2450123.7 0.0 (JD method)
33 ** 2451545.0 -1421.3 (J2000 method)
34 ** 2400000.5 50123.2 (MJD method)
35 ** 2450123.5 0.2 (date & time method)
36 **
37 ** The JD method is the most natural and convenient to use in
38 ** cases where the loss of several decimal digits of resolution is
39 ** acceptable. The J2000 and MJD methods are good compromises
40 ** between resolution and convenience. In the case of uta,utb, the
41 ** date & time method is best matched to the Earth rotation angle
42 ** algorithm used: maximum precision is delivered when the uta
43 ** argument is for 0hrs UT1 on the day in question and the utb
44 ** argument lies in the range 0 to 1, or vice versa.
45 **
46 ** 2) The caller is responsible for providing the nutation components;
47 ** they are in longitude and obliquity, in radians and are with
48 ** respect to the equinox and ecliptic of date. For high-accuracy
49 ** applications, free core nutation should be included as well as
50 ** any other relevant corrections to the position of the CIP.
51 **
52 ** 3) The arguments xp and yp are the coordinates (in radians) of the
53 ** Celestial Intermediate Pole with respect to the International
54 ** Terrestrial Reference System (see IERS Conventions 2003),
55 ** measured along the meridians to 0 and 90 deg west respectively.
56 **
57 ** 4) The matrix rc2t transforms from celestial to terrestrial
58 ** coordinates:
59 **
60 ** [TRS] = RPOM * R_3(GST) * RBPN * [CRS]
61 **
62 ** = rc2t * [CRS]
63 **
64 ** where [CRS] is a vector in the Geocentric Celestial Reference
65 ** System and [TRS] is a vector in the International Terrestrial
66 ** Reference System (see IERS Conventions 2003), RBPN is the
67 ** bias-precession-nutation matrix, GST is the Greenwich (apparent)
68 ** Sidereal Time and RPOM is the polar motion matrix.
69 **
70 ** 5) Although its name does not include "00", This function is in fact
71 ** specific to the IAU 2000 models.
72 **
73 ** Called:
74 ** eraPn00 bias/precession/nutation results, IAU 2000
75 ** eraGmst00 Greenwich mean sidereal time, IAU 2000
76 ** eraSp00 the TIO locator s', IERS 2000
77 ** eraEe00 equation of the equinoxes, IAU 2000
78 ** eraPom00 polar motion matrix
79 ** eraC2teqx form equinox-based celestial-to-terrestrial matrix
80 **
81 ** Reference:
82 **
83 ** McCarthy, D. D., Petit, G. (eds.), IERS Conventions (2003),
84 ** IERS Technical Note No. 32, BKG (2004)
85 **
86 ** Copyright (C) 2013-2020, NumFOCUS Foundation.
87 ** Derived, with permission, from the SOFA library. See notes at end of file.
88 */
89 {
90 double epsa, rb[3][3], rp[3][3], rbp[3][3], rn[3][3],
91 rbpn[3][3], gmst, ee, sp, rpom[3][3];
92
93
94 /* Form the celestial-to-true matrix for this TT. */
95 eraPn00(tta, ttb, dpsi, deps, &epsa, rb, rp, rbp, rn, rbpn);
96
97 /* Predict the Greenwich Mean Sidereal Time for this UT1 and TT. */
98 gmst = eraGmst00(uta, utb, tta, ttb);
99
100 /* Predict the equation of the equinoxes given TT and nutation. */
101 ee = eraEe00(tta, ttb, epsa, dpsi);
102
103 /* Estimate s'. */
104 sp = eraSp00(tta, ttb);
105
106 /* Form the polar motion matrix. */
107 eraPom00(xp, yp, sp, rpom);
108
109 /* Combine to form the celestial-to-terrestrial matrix. */
110 eraC2teqx(rbpn, gmst + ee, rpom, rc2t);
111
112 return;
113
114 }
115 /*----------------------------------------------------------------------
116 **
117 **
118 ** Copyright (C) 2013-2020, NumFOCUS Foundation.
119 ** All rights reserved.
120 **
121 ** This library is derived, with permission, from the International
122 ** Astronomical Union's "Standards of Fundamental Astronomy" library,
123 ** available from http://www.iausofa.org.
124 **
125 ** The ERFA version is intended to retain identical functionality to
126 ** the SOFA library, but made distinct through different function and
127 ** file names, as set out in the SOFA license conditions. The SOFA
128 ** original has a role as a reference standard for the IAU and IERS,
129 ** and consequently redistribution is permitted only in its unaltered
130 ** state. The ERFA version is not subject to this restriction and
131 ** therefore can be included in distributions which do not support the
132 ** concept of "read only" software.
133 **
134 ** Although the intent is to replicate the SOFA API (other than
135 ** replacement of prefix names) and results (with the exception of
136 ** bugs; any that are discovered will be fixed), SOFA is not
137 ** responsible for any errors found in this version of the library.
138 **
139 ** If you wish to acknowledge the SOFA heritage, please acknowledge
140 ** that you are using a library derived from SOFA, rather than SOFA
141 ** itself.
142 **
143 **
144 ** TERMS AND CONDITIONS
145 **
146 ** Redistribution and use in source and binary forms, with or without
147 ** modification, are permitted provided that the following conditions
148 ** are met:
149 **
150 ** 1 Redistributions of source code must retain the above copyright
151 ** notice, this list of conditions and the following disclaimer.
152 **
153 ** 2 Redistributions in binary form must reproduce the above copyright
154 ** notice, this list of conditions and the following disclaimer in
155 ** the documentation and/or other materials provided with the
156 ** distribution.
157 **
158 ** 3 Neither the name of the Standards Of Fundamental Astronomy Board,
159 ** the International Astronomical Union nor the names of its
160 ** contributors may be used to endorse or promote products derived
161 ** from this software without specific prior written permission.
162 **
163 ** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
164 ** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
165 ** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
166 ** FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
167 ** COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
168 ** INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
169 ** BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
170 ** LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
171 ** CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
172 ** LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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174 ** POSSIBILITY OF SUCH DAMAGE.
175 **
176 */
177