source: branches/FACT++_lidctrl_usb/erfa/src/apcg.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: 7.5 KB
Line 
1#include "erfa.h"
2
3void eraApcg(double date1, double date2,
4 double ebpv[2][3], double ehp[3],
5 eraASTROM *astrom)
6/*
7** - - - - - - - -
8** e r a A p c g
9** - - - - - - - -
10**
11** For a geocentric observer, prepare star-independent astrometry
12** parameters for transformations between ICRS and GCRS coordinates.
13** The Earth ephemeris is supplied by the caller.
14**
15** The parameters produced by this function are required in the
16** parallax, light deflection and aberration parts of the astrometric
17** transformation chain.
18**
19** Given:
20** date1 double TDB as a 2-part...
21** date2 double ...Julian Date (Note 1)
22** ebpv double[2][3] Earth barycentric pos/vel (au, au/day)
23** ehp double[3] Earth heliocentric position (au)
24**
25** Returned:
26** astrom eraASTROM* star-independent astrometry parameters:
27** pmt double PM time interval (SSB, Julian years)
28** eb double[3] SSB to observer (vector, au)
29** eh double[3] Sun to observer (unit vector)
30** em double distance from Sun to observer (au)
31** v double[3] barycentric observer velocity (vector, c)
32** bm1 double sqrt(1-|v|^2): reciprocal of Lorenz factor
33** bpn double[3][3] bias-precession-nutation matrix
34** along double unchanged
35** xpl double unchanged
36** ypl double unchanged
37** sphi double unchanged
38** cphi double unchanged
39** diurab double unchanged
40** eral double unchanged
41** refa double unchanged
42** refb double unchanged
43**
44** Notes:
45**
46** 1) The TDB date date1+date2 is a Julian Date, apportioned in any
47** convenient way between the two arguments. For example,
48** JD(TDB)=2450123.7 could be expressed in any of these ways, among
49** others:
50**
51** date1 date2
52**
53** 2450123.7 0.0 (JD method)
54** 2451545.0 -1421.3 (J2000 method)
55** 2400000.5 50123.2 (MJD method)
56** 2450123.5 0.2 (date & time method)
57**
58** The JD method is the most natural and convenient to use in cases
59** where the loss of several decimal digits of resolution is
60** acceptable. The J2000 method is best matched to the way the
61** argument is handled internally and will deliver the optimum
62** resolution. The MJD method and the date & time methods are both
63** good compromises between resolution and convenience. For most
64** applications of this function the choice will not be at all
65** critical.
66**
67** TT can be used instead of TDB without any significant impact on
68** accuracy.
69**
70** 2) All the vectors are with respect to BCRS axes.
71**
72** 3) This is one of several functions that inserts into the astrom
73** structure star-independent parameters needed for the chain of
74** astrometric transformations ICRS <-> GCRS <-> CIRS <-> observed.
75**
76** The various functions support different classes of observer and
77** portions of the transformation chain:
78**
79** functions observer transformation
80**
81** eraApcg eraApcg13 geocentric ICRS <-> GCRS
82** eraApci eraApci13 terrestrial ICRS <-> CIRS
83** eraApco eraApco13 terrestrial ICRS <-> observed
84** eraApcs eraApcs13 space ICRS <-> GCRS
85** eraAper eraAper13 terrestrial update Earth rotation
86** eraApio eraApio13 terrestrial CIRS <-> observed
87**
88** Those with names ending in "13" use contemporary ERFA models to
89** compute the various ephemerides. The others accept ephemerides
90** supplied by the caller.
91**
92** The transformation from ICRS to GCRS covers space motion,
93** parallax, light deflection, and aberration. From GCRS to CIRS
94** comprises frame bias and precession-nutation. From CIRS to
95** observed takes account of Earth rotation, polar motion, diurnal
96** aberration and parallax (unless subsumed into the ICRS <-> GCRS
97** transformation), and atmospheric refraction.
98**
99** 4) The context structure astrom produced by this function is used by
100** eraAtciq* and eraAticq*.
101**
102** Called:
103** eraApcs astrometry parameters, ICRS-GCRS, space observer
104**
105** Copyright (C) 2013-2016, NumFOCUS Foundation.
106** Derived, with permission, from the SOFA library. See notes at end of file.
107*/
108{
109/* Geocentric observer */
110 double pv[2][3] = { { 0.0, 0.0, 0.0 },
111 { 0.0, 0.0, 0.0 } };
112
113
114/* Compute the star-independent astrometry parameters. */
115 eraApcs(date1, date2, pv, ebpv, ehp, astrom);
116
117/* Finished. */
118
119}
120/*----------------------------------------------------------------------
121**
122**
123** Copyright (C) 2013-2016, NumFOCUS Foundation.
124** All rights reserved.
125**
126** This library is derived, with permission, from the International
127** Astronomical Union's "Standards of Fundamental Astronomy" library,
128** available from http://www.iausofa.org.
129**
130** The ERFA version is intended to retain identical functionality to
131** the SOFA library, but made distinct through different function and
132** file names, as set out in the SOFA license conditions. The SOFA
133** original has a role as a reference standard for the IAU and IERS,
134** and consequently redistribution is permitted only in its unaltered
135** state. The ERFA version is not subject to this restriction and
136** therefore can be included in distributions which do not support the
137** concept of "read only" software.
138**
139** Although the intent is to replicate the SOFA API (other than
140** replacement of prefix names) and results (with the exception of
141** bugs; any that are discovered will be fixed), SOFA is not
142** responsible for any errors found in this version of the library.
143**
144** If you wish to acknowledge the SOFA heritage, please acknowledge
145** that you are using a library derived from SOFA, rather than SOFA
146** itself.
147**
148**
149** TERMS AND CONDITIONS
150**
151** Redistribution and use in source and binary forms, with or without
152** modification, are permitted provided that the following conditions
153** are met:
154**
155** 1 Redistributions of source code must retain the above copyright
156** notice, this list of conditions and the following disclaimer.
157**
158** 2 Redistributions in binary form must reproduce the above copyright
159** notice, this list of conditions and the following disclaimer in
160** the documentation and/or other materials provided with the
161** distribution.
162**
163** 3 Neither the name of the Standards Of Fundamental Astronomy Board,
164** the International Astronomical Union nor the names of its
165** contributors may be used to endorse or promote products derived
166** from this software without specific prior written permission.
167**
168** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
169** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
170** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
171** FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
172** COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
173** INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
174** BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
175** LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
176** CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
177** LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
178** ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
179** POSSIBILITY OF SUCH DAMAGE.
180**
181*/
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