FACT++  1.0
atci13.c
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1 #include "erfa.h"
2 
3 void 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
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156 ** POSSIBILITY OF SUCH DAMAGE.
157 **
158 */
eraAtci13
void eraAtci13(double rc, double dc, double pr, double pd, double px, double rv, double date1, double date2, double *ri, double *di, double *eo)
Definition: atci13.c:3
eraAtciq
void eraAtciq(double rc, double dc, double pr, double pd, double px, double rv, eraASTROM *astrom, double *ri, double *di)
Definition: atciq.c:3
eraApci13
void eraApci13(double date1, double date2, eraASTROM *astrom, double *eo)
Definition: apci13.c:3