source: trunk/FACT++/sofa/src/c2tpe.c@ 18365

Last change on this file since 18365 was 18346, checked in by tbretz, 10 years ago
File size: 8.6 KB
Line 
1#include "sofa.h"
2
3void iauC2tpe(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** i a u 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** This function is part of the International Astronomical Union's
15** SOFA (Standards Of Fundamental Astronomy) software collection.
16**
17** Status: support function.
18**
19** Given:
20** tta,ttb double TT as a 2-part Julian Date (Note 1)
21** uta,utb double UT1 as a 2-part Julian Date (Note 1)
22** dpsi,deps double nutation (Note 2)
23** xp,yp double coordinates of the pole (radians, Note 3)
24**
25** Returned:
26** rc2t double[3][3] celestial-to-terrestrial matrix (Note 4)
27**
28** Notes:
29**
30** 1) The TT and UT1 dates tta+ttb and uta+utb are Julian Dates,
31** apportioned in any convenient way between the arguments uta and
32** utb. For example, JD(UT1)=2450123.7 could be expressed in any of
33** these ways, among others:
34**
35** uta utb
36**
37** 2450123.7 0.0 (JD method)
38** 2451545.0 -1421.3 (J2000 method)
39** 2400000.5 50123.2 (MJD method)
40** 2450123.5 0.2 (date & time method)
41**
42** The JD method is the most natural and convenient to use in
43** cases where the loss of several decimal digits of resolution is
44** acceptable. The J2000 and MJD methods are good compromises
45** between resolution and convenience. In the case of uta,utb, the
46** date & time method is best matched to the Earth rotation angle
47** algorithm used: maximum precision is delivered when the uta
48** argument is for 0hrs UT1 on the day in question and the utb
49** argument lies in the range 0 to 1, or vice versa.
50**
51** 2) The caller is responsible for providing the nutation components;
52** they are in longitude and obliquity, in radians and are with
53** respect to the equinox and ecliptic of date. For high-accuracy
54** applications, free core nutation should be included as well as
55** any other relevant corrections to the position of the CIP.
56**
57** 3) The arguments xp and yp are the coordinates (in radians) of the
58** Celestial Intermediate Pole with respect to the International
59** Terrestrial Reference System (see IERS Conventions 2003),
60** measured along the meridians to 0 and 90 deg west respectively.
61**
62** 4) The matrix rc2t transforms from celestial to terrestrial
63** coordinates:
64**
65** [TRS] = RPOM * R_3(GST) * RBPN * [CRS]
66**
67** = rc2t * [CRS]
68**
69** where [CRS] is a vector in the Geocentric Celestial Reference
70** System and [TRS] is a vector in the International Terrestrial
71** Reference System (see IERS Conventions 2003), RBPN is the
72** bias-precession-nutation matrix, GST is the Greenwich (apparent)
73** Sidereal Time and RPOM is the polar motion matrix.
74**
75** 5) Although its name does not include "00", This function is in fact
76** specific to the IAU 2000 models.
77**
78** Called:
79** iauPn00 bias/precession/nutation results, IAU 2000
80** iauGmst00 Greenwich mean sidereal time, IAU 2000
81** iauSp00 the TIO locator s', IERS 2000
82** iauEe00 equation of the equinoxes, IAU 2000
83** iauPom00 polar motion matrix
84** iauC2teqx form equinox-based celestial-to-terrestrial matrix
85**
86** Reference:
87**
88** McCarthy, D. D., Petit, G. (eds.), IERS Conventions (2003),
89** IERS Technical Note No. 32, BKG (2004)
90**
91** This revision: 2013 June 18
92**
93** SOFA release 2015-02-09
94**
95** Copyright (C) 2015 IAU SOFA Board. See notes at end.
96*/
97{
98 double epsa, rb[3][3], rp[3][3], rbp[3][3], rn[3][3],
99 rbpn[3][3], gmst, ee, sp, rpom[3][3];
100
101/* Form the celestial-to-true matrix for this TT. */
102 iauPn00(tta, ttb, dpsi, deps, &epsa, rb, rp, rbp, rn, rbpn);
103
104/* Predict the Greenwich Mean Sidereal Time for this UT1 and TT. */
105 gmst = iauGmst00(uta, utb, tta, ttb);
106
107/* Predict the equation of the equinoxes given TT and nutation. */
108 ee = iauEe00(tta, ttb, epsa, dpsi);
109
110/* Estimate s'. */
111 sp = iauSp00(tta, ttb);
112
113/* Form the polar motion matrix. */
114 iauPom00(xp, yp, sp, rpom);
115
116/* Combine to form the celestial-to-terrestrial matrix. */
117 iauC2teqx(rbpn, gmst + ee, rpom, rc2t);
118
119 return;
120
121/*----------------------------------------------------------------------
122**
123** Copyright (C) 2015
124** Standards Of Fundamental Astronomy Board
125** of the International Astronomical Union.
126**
127** =====================
128** SOFA Software License
129** =====================
130**
131** NOTICE TO USER:
132**
133** BY USING THIS SOFTWARE YOU ACCEPT THE FOLLOWING SIX TERMS AND
134** CONDITIONS WHICH APPLY TO ITS USE.
135**
136** 1. The Software is owned by the IAU SOFA Board ("SOFA").
137**
138** 2. Permission is granted to anyone to use the SOFA software for any
139** purpose, including commercial applications, free of charge and
140** without payment of royalties, subject to the conditions and
141** restrictions listed below.
142**
143** 3. You (the user) may copy and distribute SOFA source code to others,
144** and use and adapt its code and algorithms in your own software,
145** on a world-wide, royalty-free basis. That portion of your
146** distribution that does not consist of intact and unchanged copies
147** of SOFA source code files is a "derived work" that must comply
148** with the following requirements:
149**
150** a) Your work shall be marked or carry a statement that it
151** (i) uses routines and computations derived by you from
152** software provided by SOFA under license to you; and
153** (ii) does not itself constitute software provided by and/or
154** endorsed by SOFA.
155**
156** b) The source code of your derived work must contain descriptions
157** of how the derived work is based upon, contains and/or differs
158** from the original SOFA software.
159**
160** c) The names of all routines in your derived work shall not
161** include the prefix "iau" or "sofa" or trivial modifications
162** thereof such as changes of case.
163**
164** d) The origin of the SOFA components of your derived work must
165** not be misrepresented; you must not claim that you wrote the
166** original software, nor file a patent application for SOFA
167** software or algorithms embedded in the SOFA software.
168**
169** e) These requirements must be reproduced intact in any source
170** distribution and shall apply to anyone to whom you have
171** granted a further right to modify the source code of your
172** derived work.
173**
174** Note that, as originally distributed, the SOFA software is
175** intended to be a definitive implementation of the IAU standards,
176** and consequently third-party modifications are discouraged. All
177** variations, no matter how minor, must be explicitly marked as
178** such, as explained above.
179**
180** 4. You shall not cause the SOFA software to be brought into
181** disrepute, either by misuse, or use for inappropriate tasks, or
182** by inappropriate modification.
183**
184** 5. The SOFA software is provided "as is" and SOFA makes no warranty
185** as to its use or performance. SOFA does not and cannot warrant
186** the performance or results which the user may obtain by using the
187** SOFA software. SOFA makes no warranties, express or implied, as
188** to non-infringement of third party rights, merchantability, or
189** fitness for any particular purpose. In no event will SOFA be
190** liable to the user for any consequential, incidental, or special
191** damages, including any lost profits or lost savings, even if a
192** SOFA representative has been advised of such damages, or for any
193** claim by any third party.
194**
195** 6. The provision of any version of the SOFA software under the terms
196** and conditions specified herein does not imply that future
197** versions will also be made available under the same terms and
198** conditions.
199*
200** In any published work or commercial product which uses the SOFA
201** software directly, acknowledgement (see www.iausofa.org) is
202** appreciated.
203**
204** Correspondence concerning SOFA software should be addressed as
205** follows:
206**
207** By email: sofa@ukho.gov.uk
208** By post: IAU SOFA Center
209** HM Nautical Almanac Office
210** UK Hydrographic Office
211** Admiralty Way, Taunton
212** Somerset, TA1 2DN
213** United Kingdom
214**
215**--------------------------------------------------------------------*/
216}
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