source: trunk/FACT++/erfa/src/atciqz.c@ 18403

Last change on this file since 18403 was 18348, checked in by tbretz, 9 years ago
File size: 6.1 KB
Line 
1#include "erfa.h"
2
3void eraAtciqz(double rc, double dc, eraASTROM *astrom,
4 double *ri, double *di)
5/*
6** - - - - - - - - - -
7** e r a A t c i q z
8** - - - - - - - - - -
9**
10** Quick ICRS to CIRS transformation, given precomputed star-
11** independent astrometry parameters, and assuming zero parallax and
12** proper motion.
13**
14** Use of this function is appropriate when efficiency is important and
15** where many star positions are to be transformed for one date. The
16** star-independent parameters can be obtained by calling one of the
17** functions eraApci[13], eraApcg[13], eraApco[13] or eraApcs[13].
18**
19** The corresponding function for the case of non-zero parallax and
20** proper motion is eraAtciq.
21**
22** Given:
23** rc,dc double ICRS astrometric RA,Dec (radians)
24** astrom eraASTROM* star-independent astrometry parameters:
25** pmt double PM time interval (SSB, Julian years)
26** eb double[3] SSB to observer (vector, au)
27** eh double[3] Sun to observer (unit vector)
28** em double distance from Sun to observer (au)
29** v double[3] barycentric observer velocity (vector, c)
30** bm1 double sqrt(1-|v|^2): reciprocal of Lorenz factor
31** bpn double[3][3] bias-precession-nutation matrix
32** along double longitude + s' (radians)
33** xpl double polar motion xp wrt local meridian (radians)
34** ypl double polar motion yp wrt local meridian (radians)
35** sphi double sine of geodetic latitude
36** cphi double cosine of geodetic latitude
37** diurab double magnitude of diurnal aberration vector
38** eral double "local" Earth rotation angle (radians)
39** refa double refraction constant A (radians)
40** refb double refraction constant B (radians)
41**
42** Returned:
43** ri,di double CIRS RA,Dec (radians)
44**
45** Note:
46**
47** All the vectors are with respect to BCRS axes.
48**
49** References:
50**
51** Urban, S. & Seidelmann, P. K. (eds), Explanatory Supplement to
52** the Astronomical Almanac, 3rd ed., University Science Books
53** (2013).
54**
55** Klioner, Sergei A., "A practical relativistic model for micro-
56** arcsecond astrometry in space", Astr. J. 125, 1580-1597 (2003).
57**
58** Called:
59** eraS2c spherical coordinates to unit vector
60** eraLdsun light deflection due to Sun
61** eraAb stellar aberration
62** eraRxp product of r-matrix and p-vector
63** eraC2s p-vector to spherical
64** eraAnp normalize angle into range +/- pi
65**
66** Copyright (C) 2013-2015, NumFOCUS Foundation.
67** Derived, with permission, from the SOFA library. See notes at end of file.
68*/
69{
70 double pco[3], pnat[3], ppr[3], pi[3], w;
71
72/* BCRS coordinate direction (unit vector). */
73 eraS2c(rc, dc, pco);
74
75/* Light deflection by the Sun, giving BCRS natural direction. */
76 eraLdsun(pco, astrom->eh, astrom->em, pnat);
77
78/* Aberration, giving GCRS proper direction. */
79 eraAb(pnat, astrom->v, astrom->em, astrom->bm1, ppr);
80
81/* Bias-precession-nutation, giving CIRS proper direction. */
82 eraRxp(astrom->bpn, ppr, pi);
83
84/* CIRS RA,Dec. */
85 eraC2s(pi, &w, di);
86 *ri = eraAnp(w);
87
88/* Finished. */
89
90}
91/*----------------------------------------------------------------------
92**
93**
94** Copyright (C) 2013-2015, NumFOCUS Foundation.
95** All rights reserved.
96**
97** This library is derived, with permission, from the International
98** Astronomical Union's "Standards of Fundamental Astronomy" library,
99** available from http://www.iausofa.org.
100**
101** The ERFA version is intended to retain identical functionality to
102** the SOFA library, but made distinct through different function and
103** file names, as set out in the SOFA license conditions. The SOFA
104** original has a role as a reference standard for the IAU and IERS,
105** and consequently redistribution is permitted only in its unaltered
106** state. The ERFA version is not subject to this restriction and
107** therefore can be included in distributions which do not support the
108** concept of "read only" software.
109**
110** Although the intent is to replicate the SOFA API (other than
111** replacement of prefix names) and results (with the exception of
112** bugs; any that are discovered will be fixed), SOFA is not
113** responsible for any errors found in this version of the library.
114**
115** If you wish to acknowledge the SOFA heritage, please acknowledge
116** that you are using a library derived from SOFA, rather than SOFA
117** itself.
118**
119**
120** TERMS AND CONDITIONS
121**
122** Redistribution and use in source and binary forms, with or without
123** modification, are permitted provided that the following conditions
124** are met:
125**
126** 1 Redistributions of source code must retain the above copyright
127** notice, this list of conditions and the following disclaimer.
128**
129** 2 Redistributions in binary form must reproduce the above copyright
130** notice, this list of conditions and the following disclaimer in
131** the documentation and/or other materials provided with the
132** distribution.
133**
134** 3 Neither the name of the Standards Of Fundamental Astronomy Board,
135** the International Astronomical Union nor the names of its
136** contributors may be used to endorse or promote products derived
137** from this software without specific prior written permission.
138**
139** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
140** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
141** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
142** FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
143** COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
144** INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
145** BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
146** LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
147** CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
148** LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
149** ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
150** POSSIBILITY OF SUCH DAMAGE.
151**
152*/
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