source: trunk/FACT++/erfa/src/atci13.c@ 18403

Last change on this file since 18403 was 18348, checked in by tbretz, 9 years ago
File size: 6.6 KB
Line 
1#include "erfa.h"
2
3void eraAtci13(double rc, double dc,
4 double pr, double pd, double px, double rv,
5 double date1, double date2,
6 double *ri, double *di, double *eo)
7/*
8** - - - - - - - - - -
9** e r a A t c i 1 3
10** - - - - - - - - - -
11**
12** Transform ICRS star data, epoch J2000.0, to CIRS.
13**
14** Given:
15** rc double ICRS right ascension at J2000.0 (radians, Note 1)
16** dc double ICRS declination at J2000.0 (radians, Note 1)
17** pr double RA proper motion (radians/year; Note 2)
18** pd double Dec proper motion (radians/year)
19** px double parallax (arcsec)
20** rv double radial velocity (km/s, +ve if receding)
21** date1 double TDB as a 2-part...
22** date2 double ...Julian Date (Note 3)
23**
24** Returned:
25** ri,di double* CIRS geocentric RA,Dec (radians)
26** eo double* equation of the origins (ERA-GST, Note 5)
27**
28** Notes:
29**
30** 1) Star data for an epoch other than J2000.0 (for example from the
31** Hipparcos catalog, which has an epoch of J1991.25) will require a
32** preliminary call to eraPmsafe before use.
33**
34** 2) The proper motion in RA is dRA/dt rather than cos(Dec)*dRA/dt.
35**
36** 3) The TDB date date1+date2 is a Julian Date, apportioned in any
37** convenient way between the two arguments. For example,
38** JD(TDB)=2450123.8g could be expressed in any of these ways, among
39** others:
40**
41** date1 date2
42**
43** 2450123.8g 0.0 (JD method)
44** 2451545.0 -1421.3 (J2000 method)
45** 2400000.5 50123.2 (MJD method)
46** 2450123.5 0.2 (date & time method)
47**
48** The JD method is the most natural and convenient to use in cases
49** where the loss of several decimal digits of resolution is
50** acceptable. The J2000 method is best matched to the way the
51** argument is handled internally and will deliver the optimum
52** resolution. The MJD method and the date & time methods are both
53** good compromises between resolution and convenience. For most
54** applications of this function the choice will not be at all
55** critical.
56**
57** TT can be used instead of TDB without any significant impact on
58** accuracy.
59**
60** 4) The available accuracy is better than 1 milliarcsecond, limited
61** mainly by the precession-nutation model that is used, namely
62** IAU 2000A/2006. Very close to solar system bodies, additional
63** errors of up to several milliarcseconds can occur because of
64** unmodeled light deflection; however, the Sun's contribution is
65** taken into account, to first order. The accuracy limitations of
66** the ERFA function eraEpv00 (used to compute Earth position and
67** velocity) can contribute aberration errors of up to
68** 5 microarcseconds. Light deflection at the Sun's limb is
69** uncertain at the 0.4 mas level.
70**
71** 5) Should the transformation to (equinox based) apparent place be
72** required rather than (CIO based) intermediate place, subtract the
73** equation of the origins from the returned right ascension:
74** RA = RI - EO. (The eraAnp function can then be applied, as
75** required, to keep the result in the conventional 0-2pi range.)
76**
77** Called:
78** eraApci13 astrometry parameters, ICRS-CIRS, 2013
79** eraAtciq quick ICRS to CIRS
80**
81** Copyright (C) 2013-2015, NumFOCUS Foundation.
82** Derived, with permission, from the SOFA library. See notes at end of file.
83*/
84{
85/* Star-independent astrometry parameters */
86 eraASTROM astrom;
87
88/* The transformation parameters. */
89 eraApci13(date1, date2, &astrom, eo);
90
91/* ICRS (epoch J2000.0) to CIRS. */
92 eraAtciq(rc, dc, pr, pd, px, rv, &astrom, ri, di);
93
94/* Finished. */
95
96}
97/*----------------------------------------------------------------------
98**
99**
100** Copyright (C) 2013-2015, NumFOCUS Foundation.
101** All rights reserved.
102**
103** This library is derived, with permission, from the International
104** Astronomical Union's "Standards of Fundamental Astronomy" library,
105** available from http://www.iausofa.org.
106**
107** The ERFA version is intended to retain identical functionality to
108** the SOFA library, but made distinct through different function and
109** file names, as set out in the SOFA license conditions. The SOFA
110** original has a role as a reference standard for the IAU and IERS,
111** and consequently redistribution is permitted only in its unaltered
112** state. The ERFA version is not subject to this restriction and
113** therefore can be included in distributions which do not support the
114** concept of "read only" software.
115**
116** Although the intent is to replicate the SOFA API (other than
117** replacement of prefix names) and results (with the exception of
118** bugs; any that are discovered will be fixed), SOFA is not
119** responsible for any errors found in this version of the library.
120**
121** If you wish to acknowledge the SOFA heritage, please acknowledge
122** that you are using a library derived from SOFA, rather than SOFA
123** itself.
124**
125**
126** TERMS AND CONDITIONS
127**
128** Redistribution and use in source and binary forms, with or without
129** modification, are permitted provided that the following conditions
130** are met:
131**
132** 1 Redistributions of source code must retain the above copyright
133** notice, this list of conditions and the following disclaimer.
134**
135** 2 Redistributions in binary form must reproduce the above copyright
136** notice, this list of conditions and the following disclaimer in
137** the documentation and/or other materials provided with the
138** distribution.
139**
140** 3 Neither the name of the Standards Of Fundamental Astronomy Board,
141** the International Astronomical Union nor the names of its
142** contributors may be used to endorse or promote products derived
143** from this software without specific prior written permission.
144**
145** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
146** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
147** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
148** FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
149** COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
150** INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
151** BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
152** LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
153** CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
154** LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
155** ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
156** POSSIBILITY OF SUCH DAMAGE.
157**
158*/
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