source: branches/FACT++_lidctrl_usb/erfa/src/c2t06a.c@ 19875

Last change on this file since 19875 was 18711, checked in by tbretz, 10 years ago
Updated to ERFA 1.3.0 (no relevant code change except the leap second at the beginning of 2017)
File size: 6.4 KB
Line 
1#include "erfa.h"
2
3void 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) 2013-2016, 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
82/* Form the celestial-to-intermediate matrix for this TT. */
83 eraC2i06a(tta, ttb, rc2i);
84
85/* Predict the Earth rotation angle for this UT1. */
86 era = eraEra00(uta, utb);
87
88/* Estimate s'. */
89 sp = eraSp00(tta, ttb);
90
91/* Form the polar motion matrix. */
92 eraPom00(xp, yp, sp, rpom);
93
94/* Combine to form the celestial-to-terrestrial matrix. */
95 eraC2tcio(rc2i, era, rpom, rc2t);
96
97 return;
98
99}
100/*----------------------------------------------------------------------
101**
102**
103** Copyright (C) 2013-2016, NumFOCUS Foundation.
104** All rights reserved.
105**
106** This library is derived, with permission, from the International
107** Astronomical Union's "Standards of Fundamental Astronomy" library,
108** available from http://www.iausofa.org.
109**
110** The ERFA version is intended to retain identical functionality to
111** the SOFA library, but made distinct through different function and
112** file names, as set out in the SOFA license conditions. The SOFA
113** original has a role as a reference standard for the IAU and IERS,
114** and consequently redistribution is permitted only in its unaltered
115** state. The ERFA version is not subject to this restriction and
116** therefore can be included in distributions which do not support the
117** concept of "read only" software.
118**
119** Although the intent is to replicate the SOFA API (other than
120** replacement of prefix names) and results (with the exception of
121** bugs; any that are discovered will be fixed), SOFA is not
122** responsible for any errors found in this version of the library.
123**
124** If you wish to acknowledge the SOFA heritage, please acknowledge
125** that you are using a library derived from SOFA, rather than SOFA
126** itself.
127**
128**
129** TERMS AND CONDITIONS
130**
131** Redistribution and use in source and binary forms, with or without
132** modification, are permitted provided that the following conditions
133** are met:
134**
135** 1 Redistributions of source code must retain the above copyright
136** notice, this list of conditions and the following disclaimer.
137**
138** 2 Redistributions in binary form must reproduce the above copyright
139** notice, this list of conditions and the following disclaimer in
140** the documentation and/or other materials provided with the
141** distribution.
142**
143** 3 Neither the name of the Standards Of Fundamental Astronomy Board,
144** the International Astronomical Union nor the names of its
145** contributors may be used to endorse or promote products derived
146** from this software without specific prior written permission.
147**
148** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
149** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
150** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
151** FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
152** COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
153** INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
154** BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
155** LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
156** CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
157** LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
158** ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
159** POSSIBILITY OF SUCH DAMAGE.
160**
161*/
Note: See TracBrowser for help on using the repository browser.