FACT++  1.0
c2t06a.c
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1 #include "erfa.h"
2 
3 void eraC2t06a(double tta, double ttb, double uta, double utb,
4  double xp, double yp, double rc2t[3][3])
5 /*
6 ** - - - - - - - - - -
7 ** e r a C 2 t 0 6 a
8 ** - - - - - - - - - -
9 **
10 ** Form the celestial to terrestrial matrix given the date, the UT1 and
11 ** the polar motion, using the IAU 2006 precession and IAU 2000A
12 ** nutation models.
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 ** xp,yp double coordinates of the pole (radians, Note 2)
18 **
19 ** Returned:
20 ** rc2t double[3][3] celestial-to-terrestrial matrix (Note 3)
21 **
22 ** Notes:
23 **
24 ** 1) The TT and UT1 dates tta+ttb and uta+utb are Julian Dates,
25 ** apportioned in any convenient way between the arguments uta and
26 ** utb. For example, JD(UT1)=2450123.7 could be expressed in any of
27 ** these ways, among others:
28 **
29 ** uta utb
30 **
31 ** 2450123.7 0.0 (JD method)
32 ** 2451545.0 -1421.3 (J2000 method)
33 ** 2400000.5 50123.2 (MJD method)
34 ** 2450123.5 0.2 (date & time method)
35 **
36 ** The JD method is the most natural and convenient to use in
37 ** cases where the loss of several decimal digits of resolution is
38 ** acceptable. The J2000 and MJD methods are good compromises
39 ** between resolution and convenience. In the case of uta,utb, the
40 ** date & time method is best matched to the Earth rotation angle
41 ** algorithm used: maximum precision is delivered when the uta
42 ** argument is for 0hrs UT1 on the day in question and the utb
43 ** argument lies in the range 0 to 1, or vice versa.
44 **
45 ** 2) The arguments xp and yp are the coordinates (in radians) of the
46 ** Celestial Intermediate Pole with respect to the International
47 ** Terrestrial Reference System (see IERS Conventions 2003),
48 ** measured along the meridians to 0 and 90 deg west respectively.
49 **
50 ** 3) The matrix rc2t transforms from celestial to terrestrial
51 ** coordinates:
52 **
53 ** [TRS] = RPOM * R_3(ERA) * RC2I * [CRS]
54 **
55 ** = rc2t * [CRS]
56 **
57 ** where [CRS] is a vector in the Geocentric Celestial Reference
58 ** System and [TRS] is a vector in the International Terrestrial
59 ** Reference System (see IERS Conventions 2003), RC2I is the
60 ** celestial-to-intermediate matrix, ERA is the Earth rotation
61 ** angle and RPOM is the polar motion matrix.
62 **
63 ** Called:
64 ** eraC2i06a celestial-to-intermediate matrix, IAU 2006/2000A
65 ** eraEra00 Earth rotation angle, IAU 2000
66 ** eraSp00 the TIO locator s', IERS 2000
67 ** eraPom00 polar motion matrix
68 ** eraC2tcio form CIO-based celestial-to-terrestrial matrix
69 **
70 ** Reference:
71 **
72 ** McCarthy, D. D., Petit, G. (eds.), 2004, IERS Conventions (2003),
73 ** IERS Technical Note No. 32, BKG
74 **
75 ** Copyright (C) 2013-2015, NumFOCUS Foundation.
76 ** Derived, with permission, from the SOFA library. See notes at end of file.
77 */
78 {
79  double rc2i[3][3], era, sp, rpom[3][3];
80 
81 /* Form the celestial-to-intermediate matrix for this TT. */
82  eraC2i06a(tta, ttb, rc2i);
83 
84 /* Predict the Earth rotation angle for this UT1. */
85  era = eraEra00(uta, utb);
86 
87 /* Estimate s'. */
88  sp = eraSp00(tta, ttb);
89 
90 /* Form the polar motion matrix. */
91  eraPom00(xp, yp, sp, rpom);
92 
93 /* Combine to form the celestial-to-terrestrial matrix. */
94  eraC2tcio(rc2i, era, rpom, rc2t);
95 
96  return;
97 
98 }
99 /*----------------------------------------------------------------------
100 **
101 **
102 ** Copyright (C) 2013-2015, NumFOCUS Foundation.
103 ** All rights reserved.
104 **
105 ** This library is derived, with permission, from the International
106 ** Astronomical Union's "Standards of Fundamental Astronomy" library,
107 ** available from http://www.iausofa.org.
108 **
109 ** The ERFA version is intended to retain identical functionality to
110 ** the SOFA library, but made distinct through different function and
111 ** file names, as set out in the SOFA license conditions. The SOFA
112 ** original has a role as a reference standard for the IAU and IERS,
113 ** and consequently redistribution is permitted only in its unaltered
114 ** state. The ERFA version is not subject to this restriction and
115 ** therefore can be included in distributions which do not support the
116 ** concept of "read only" software.
117 **
118 ** Although the intent is to replicate the SOFA API (other than
119 ** replacement of prefix names) and results (with the exception of
120 ** bugs; any that are discovered will be fixed), SOFA is not
121 ** responsible for any errors found in this version of the library.
122 **
123 ** If you wish to acknowledge the SOFA heritage, please acknowledge
124 ** that you are using a library derived from SOFA, rather than SOFA
125 ** itself.
126 **
127 **
128 ** TERMS AND CONDITIONS
129 **
130 ** Redistribution and use in source and binary forms, with or without
131 ** modification, are permitted provided that the following conditions
132 ** are met:
133 **
134 ** 1 Redistributions of source code must retain the above copyright
135 ** notice, this list of conditions and the following disclaimer.
136 **
137 ** 2 Redistributions in binary form must reproduce the above copyright
138 ** notice, this list of conditions and the following disclaimer in
139 ** the documentation and/or other materials provided with the
140 ** distribution.
141 **
142 ** 3 Neither the name of the Standards Of Fundamental Astronomy Board,
143 ** the International Astronomical Union nor the names of its
144 ** contributors may be used to endorse or promote products derived
145 ** from this software without specific prior written permission.
146 **
147 ** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
148 ** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
149 ** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
150 ** FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
151 ** COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
152 ** INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
153 ** BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
154 ** LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
155 ** CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
156 ** LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
157 ** ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
158 ** POSSIBILITY OF SUCH DAMAGE.
159 **
160 */
eraC2i06a
void eraC2i06a(double date1, double date2, double rc2i[3][3])
Definition: c2i06a.c:3
eraSp00
double eraSp00(double date1, double date2)
Definition: sp00.c:3
eraEra00
double eraEra00(double dj1, double dj2)
Definition: era00.c:3
eraPom00
void eraPom00(double xp, double yp, double sp, double rpom[3][3])
Definition: pom00.c:3
eraC2t06a
void eraC2t06a(double tta, double ttb, double uta, double utb, double xp, double yp, double rc2t[3][3])
Definition: c2t06a.c:3
eraC2tcio
void eraC2tcio(double rc2i[3][3], double era, double rpom[3][3], double rc2t[3][3])
Definition: c2tcio.c:3