FACT++  1.0
c2t00b.c
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1 #include "erfa.h"
2 
3 void eraC2t00b(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 0 b
8 ** - - - - - - - - - -
9 **
10 ** Form the celestial to terrestrial matrix given the date, the UT1 and
11 ** the polar motion, using the IAU 2000B nutation model.
12 **
13 ** Given:
14 ** tta,ttb double TT as a 2-part Julian Date (Note 1)
15 ** uta,utb double UT1 as a 2-part Julian Date (Note 1)
16 ** xp,yp double coordinates of the pole (radians, Note 2)
17 **
18 ** Returned:
19 ** rc2t double[3][3] celestial-to-terrestrial matrix (Note 3)
20 **
21 ** Notes:
22 **
23 ** 1) The TT and UT1 dates tta+ttb and uta+utb are Julian Dates,
24 ** apportioned in any convenient way between the arguments uta and
25 ** utb. For example, JD(UT1)=2450123.7 could be expressed in any of
26 ** these ways, among others:
27 **
28 ** uta utb
29 **
30 ** 2450123.7 0.0 (JD method)
31 ** 2451545.0 -1421.3 (J2000 method)
32 ** 2400000.5 50123.2 (MJD method)
33 ** 2450123.5 0.2 (date & time method)
34 **
35 ** The JD method is the most natural and convenient to use in
36 ** cases where the loss of several decimal digits of resolution is
37 ** acceptable. The J2000 and MJD methods are good compromises
38 ** between resolution and convenience. In the case of uta,utb, the
39 ** date & time method is best matched to the Earth rotation angle
40 ** algorithm used: maximum precision is delivered when the uta
41 ** argument is for 0hrs UT1 on the day in question and the utb
42 ** argument lies in the range 0 to 1, or vice versa.
43 **
44 ** 2) The arguments xp and yp are the coordinates (in radians) of the
45 ** Celestial Intermediate Pole with respect to the International
46 ** Terrestrial Reference System (see IERS Conventions 2003),
47 ** measured along the meridians to 0 and 90 deg west respectively.
48 **
49 ** 3) The matrix rc2t transforms from celestial to terrestrial
50 ** coordinates:
51 **
52 ** [TRS] = RPOM * R_3(ERA) * RC2I * [CRS]
53 **
54 ** = rc2t * [CRS]
55 **
56 ** where [CRS] is a vector in the Geocentric Celestial Reference
57 ** System and [TRS] is a vector in the International Terrestrial
58 ** Reference System (see IERS Conventions 2003), RC2I is the
59 ** celestial-to-intermediate matrix, ERA is the Earth rotation
60 ** angle and RPOM is the polar motion matrix.
61 **
62 ** 4) The present function is faster, but slightly less accurate (about
63 ** 1 mas), than the eraC2t00a function.
64 **
65 ** Called:
66 ** eraC2i00b celestial-to-intermediate matrix, IAU 2000B
67 ** eraEra00 Earth rotation angle, IAU 2000
68 ** eraPom00 polar motion matrix
69 ** eraC2tcio form CIO-based celestial-to-terrestrial matrix
70 **
71 ** Reference:
72 **
73 ** McCarthy, D. D., Petit, G. (eds.), IERS Conventions (2003),
74 ** IERS Technical Note No. 32, BKG (2004)
75 **
76 ** Copyright (C) 2013-2015, NumFOCUS Foundation.
77 ** Derived, with permission, from the SOFA library. See notes at end of file.
78 */
79 {
80  double rc2i[3][3], era, rpom[3][3];
81 
82 /* Form the celestial-to-intermediate matrix for this TT (IAU 2000B). */
83  eraC2i00b(tta, ttb, rc2i);
84 
85 /* Predict the Earth rotation angle for this UT1. */
86  era = eraEra00(uta, utb);
87 
88 /* Form the polar motion matrix (neglecting s'). */
89  eraPom00(xp, yp, 0.0, rpom);
90 
91 /* Combine to form the celestial-to-terrestrial matrix. */
92  eraC2tcio(rc2i, era, rpom, rc2t);
93 
94  return;
95 
96 }
97 /*----------------------------------------------------------------------
98 **
99 **
100 ** Copyright (C) 2013-2015, NumFOCUS Foundation.
101 ** All rights reserved.
102 **
103 ** This library is derived, with permission, from the International
104 ** Astronomical Union's "Standards of Fundamental Astronomy" library,
105 ** available from http://www.iausofa.org.
106 **
107 ** The ERFA version is intended to retain identical functionality to
108 ** the SOFA library, but made distinct through different function and
109 ** file names, as set out in the SOFA license conditions. The SOFA
110 ** original has a role as a reference standard for the IAU and IERS,
111 ** and consequently redistribution is permitted only in its unaltered
112 ** state. The ERFA version is not subject to this restriction and
113 ** therefore can be included in distributions which do not support the
114 ** concept of "read only" software.
115 **
116 ** Although the intent is to replicate the SOFA API (other than
117 ** replacement of prefix names) and results (with the exception of
118 ** bugs; any that are discovered will be fixed), SOFA is not
119 ** responsible for any errors found in this version of the library.
120 **
121 ** If you wish to acknowledge the SOFA heritage, please acknowledge
122 ** that you are using a library derived from SOFA, rather than SOFA
123 ** itself.
124 **
125 **
126 ** TERMS AND CONDITIONS
127 **
128 ** Redistribution and use in source and binary forms, with or without
129 ** modification, are permitted provided that the following conditions
130 ** are met:
131 **
132 ** 1 Redistributions of source code must retain the above copyright
133 ** notice, this list of conditions and the following disclaimer.
134 **
135 ** 2 Redistributions in binary form must reproduce the above copyright
136 ** notice, this list of conditions and the following disclaimer in
137 ** the documentation and/or other materials provided with the
138 ** distribution.
139 **
140 ** 3 Neither the name of the Standards Of Fundamental Astronomy Board,
141 ** the International Astronomical Union nor the names of its
142 ** contributors may be used to endorse or promote products derived
143 ** from this software without specific prior written permission.
144 **
145 ** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
146 ** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
147 ** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
148 ** FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
149 ** COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
150 ** INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
151 ** BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
152 ** LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
153 ** CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
154 ** LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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156 ** POSSIBILITY OF SUCH DAMAGE.
157 **
158 */
eraC2i00b
void eraC2i00b(double date1, double date2, double rc2i[3][3])
Definition: c2i00b.c:3
eraC2t00b
void eraC2t00b(double tta, double ttb, double uta, double utb, double xp, double yp, double rc2t[3][3])
Definition: c2t00b.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
eraC2tcio
void eraC2tcio(double rc2i[3][3], double era, double rpom[3][3], double rc2t[3][3])
Definition: c2tcio.c:3