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

Last change on this file since 18365 was 18346, checked in by tbretz, 10 years ago
File size: 8.1 KB
Line 
1#include "sofa.h"
2
3void iauAper(double theta, iauASTROM *astrom)
4/*
5** - - - - - - - -
6** i a u A p e r
7** - - - - - - - -
8**
9** In the star-independent astrometry parameters, update only the
10** Earth rotation angle, supplied by the caller explicitly.
11**
12** This function is part of the International Astronomical Union's
13** SOFA (Standards of Fundamental Astronomy) software collection.
14**
15** Status: support function.
16**
17** Given:
18** theta double Earth rotation angle (radians, Note 2)
19** astrom iauASTROM* star-independent astrometry parameters:
20** pmt double not used
21** eb double[3] not used
22** eh double[3] not used
23** em double not used
24** v double[3] not used
25** bm1 double not used
26** bpn double[3][3] not used
27** along double longitude + s' (radians)
28** xpl double not used
29** ypl double not used
30** sphi double not used
31** cphi double not used
32** diurab double not used
33** eral double not used
34** refa double not used
35** refb double not used
36**
37** Returned:
38** astrom iauASTROM* star-independent astrometry parameters:
39** pmt double unchanged
40** eb double[3] unchanged
41** eh double[3] unchanged
42** em double unchanged
43** v double[3] unchanged
44** bm1 double unchanged
45** bpn double[3][3] unchanged
46** along double unchanged
47** xpl double unchanged
48** ypl double unchanged
49** sphi double unchanged
50** cphi double unchanged
51** diurab double unchanged
52** eral double "local" Earth rotation angle (radians)
53** refa double unchanged
54** refb double unchanged
55**
56** Notes:
57**
58** 1) This function exists to enable sidereal-tracking applications to
59** avoid wasteful recomputation of the bulk of the astrometry
60** parameters: only the Earth rotation is updated.
61**
62** 2) For targets expressed as equinox based positions, such as
63** classical geocentric apparent (RA,Dec), the supplied theta can be
64** Greenwich apparent sidereal time rather than Earth rotation
65** angle.
66**
67** 3) The function iauAper13 can be used instead of the present
68** function, and starts from UT1 rather than ERA itself.
69**
70** 4) This is one of several functions that inserts into the astrom
71** structure star-independent parameters needed for the chain of
72** astrometric transformations ICRS <-> GCRS <-> CIRS <-> observed.
73**
74** The various functions support different classes of observer and
75** portions of the transformation chain:
76**
77** functions observer transformation
78**
79** iauApcg iauApcg13 geocentric ICRS <-> GCRS
80** iauApci iauApci13 terrestrial ICRS <-> CIRS
81** iauApco iauApco13 terrestrial ICRS <-> observed
82** iauApcs iauApcs13 space ICRS <-> GCRS
83** iauAper iauAper13 terrestrial update Earth rotation
84** iauApio iauApio13 terrestrial CIRS <-> observed
85**
86** Those with names ending in "13" use contemporary SOFA models to
87** compute the various ephemerides. The others accept ephemerides
88** supplied by the caller.
89**
90** The transformation from ICRS to GCRS covers space motion,
91** parallax, light deflection, and aberration. From GCRS to CIRS
92** comprises frame bias and precession-nutation. From CIRS to
93** observed takes account of Earth rotation, polar motion, diurnal
94** aberration and parallax (unless subsumed into the ICRS <-> GCRS
95** transformation), and atmospheric refraction.
96**
97** This revision: 2013 September 25
98**
99** SOFA release 2015-02-09
100**
101** Copyright (C) 2015 IAU SOFA Board. See notes at end.
102*/
103{
104 astrom->eral = theta + astrom->along;
105
106/* Finished. */
107
108/*----------------------------------------------------------------------
109**
110** Copyright (C) 2015
111** Standards Of Fundamental Astronomy Board
112** of the International Astronomical Union.
113**
114** =====================
115** SOFA Software License
116** =====================
117**
118** NOTICE TO USER:
119**
120** BY USING THIS SOFTWARE YOU ACCEPT THE FOLLOWING SIX TERMS AND
121** CONDITIONS WHICH APPLY TO ITS USE.
122**
123** 1. The Software is owned by the IAU SOFA Board ("SOFA").
124**
125** 2. Permission is granted to anyone to use the SOFA software for any
126** purpose, including commercial applications, free of charge and
127** without payment of royalties, subject to the conditions and
128** restrictions listed below.
129**
130** 3. You (the user) may copy and distribute SOFA source code to others,
131** and use and adapt its code and algorithms in your own software,
132** on a world-wide, royalty-free basis. That portion of your
133** distribution that does not consist of intact and unchanged copies
134** of SOFA source code files is a "derived work" that must comply
135** with the following requirements:
136**
137** a) Your work shall be marked or carry a statement that it
138** (i) uses routines and computations derived by you from
139** software provided by SOFA under license to you; and
140** (ii) does not itself constitute software provided by and/or
141** endorsed by SOFA.
142**
143** b) The source code of your derived work must contain descriptions
144** of how the derived work is based upon, contains and/or differs
145** from the original SOFA software.
146**
147** c) The names of all routines in your derived work shall not
148** include the prefix "iau" or "sofa" or trivial modifications
149** thereof such as changes of case.
150**
151** d) The origin of the SOFA components of your derived work must
152** not be misrepresented; you must not claim that you wrote the
153** original software, nor file a patent application for SOFA
154** software or algorithms embedded in the SOFA software.
155**
156** e) These requirements must be reproduced intact in any source
157** distribution and shall apply to anyone to whom you have
158** granted a further right to modify the source code of your
159** derived work.
160**
161** Note that, as originally distributed, the SOFA software is
162** intended to be a definitive implementation of the IAU standards,
163** and consequently third-party modifications are discouraged. All
164** variations, no matter how minor, must be explicitly marked as
165** such, as explained above.
166**
167** 4. You shall not cause the SOFA software to be brought into
168** disrepute, either by misuse, or use for inappropriate tasks, or
169** by inappropriate modification.
170**
171** 5. The SOFA software is provided "as is" and SOFA makes no warranty
172** as to its use or performance. SOFA does not and cannot warrant
173** the performance or results which the user may obtain by using the
174** SOFA software. SOFA makes no warranties, express or implied, as
175** to non-infringement of third party rights, merchantability, or
176** fitness for any particular purpose. In no event will SOFA be
177** liable to the user for any consequential, incidental, or special
178** damages, including any lost profits or lost savings, even if a
179** SOFA representative has been advised of such damages, or for any
180** claim by any third party.
181**
182** 6. The provision of any version of the SOFA software under the terms
183** and conditions specified herein does not imply that future
184** versions will also be made available under the same terms and
185** conditions.
186*
187** In any published work or commercial product which uses the SOFA
188** software directly, acknowledgement (see www.iausofa.org) is
189** appreciated.
190**
191** Correspondence concerning SOFA software should be addressed as
192** follows:
193**
194** By email: sofa@ukho.gov.uk
195** By post: IAU SOFA Center
196** HM Nautical Almanac Office
197** UK Hydrographic Office
198** Admiralty Way, Taunton
199** Somerset, TA1 2DN
200** United Kingdom
201**
202**--------------------------------------------------------------------*/
203
204}
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