FACT++  1.0
apcs13.c
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1 #include "erfa.h"
2 
3 void eraApcs13(double date1, double date2, double pv[2][3],
4  eraASTROM *astrom)
5 /*
6 ** - - - - - - - - - -
7 ** e r a A p c s 1 3
8 ** - - - - - - - - - -
9 **
10 ** For an observer whose geocentric position and velocity are known,
11 ** prepare star-independent astrometry parameters for transformations
12 ** between ICRS and GCRS. The Earth ephemeris is from ERFA models.
13 **
14 ** The parameters produced by this function are required in the space
15 ** motion, parallax, light deflection and aberration parts of the
16 ** astrometric transformation chain.
17 **
18 ** Given:
19 ** date1 double TDB as a 2-part...
20 ** date2 double ...Julian Date (Note 1)
21 ** pv double[2][3] observer's geocentric pos/vel (Note 3)
22 **
23 ** Returned:
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 unchanged
33 ** xpl double unchanged
34 ** ypl double unchanged
35 ** sphi double unchanged
36 ** cphi double unchanged
37 ** diurab double unchanged
38 ** eral double unchanged
39 ** refa double unchanged
40 ** refb double unchanged
41 **
42 ** Notes:
43 **
44 ** 1) The TDB date date1+date2 is a Julian Date, apportioned in any
45 ** convenient way between the two arguments. For example,
46 ** JD(TDB)=2450123.7 could be expressed in any of these ways, among
47 ** others:
48 **
49 ** date1 date2
50 **
51 ** 2450123.7 0.0 (JD method)
52 ** 2451545.0 -1421.3 (J2000 method)
53 ** 2400000.5 50123.2 (MJD method)
54 ** 2450123.5 0.2 (date & time method)
55 **
56 ** The JD method is the most natural and convenient to use in cases
57 ** where the loss of several decimal digits of resolution is
58 ** acceptable. The J2000 method is best matched to the way the
59 ** argument is handled internally and will deliver the optimum
60 ** resolution. The MJD method and the date & time methods are both
61 ** good compromises between resolution and convenience. For most
62 ** applications of this function the choice will not be at all
63 ** critical.
64 **
65 ** TT can be used instead of TDB without any significant impact on
66 ** accuracy.
67 **
68 ** 2) All the vectors are with respect to BCRS axes.
69 **
70 ** 3) The observer's position and velocity pv are geocentric but with
71 ** respect to BCRS axes, and in units of m and m/s. No assumptions
72 ** are made about proximity to the Earth, and the function can be
73 ** used for deep space applications as well as Earth orbit and
74 ** terrestrial.
75 **
76 ** 4) In cases where the caller wishes to supply his own Earth
77 ** ephemeris, the function eraApcs can be used instead of the present
78 ** function.
79 **
80 ** 5) This is one of several functions that inserts into the astrom
81 ** structure star-independent parameters needed for the chain of
82 ** astrometric transformations ICRS <-> GCRS <-> CIRS <-> observed.
83 **
84 ** The various functions support different classes of observer and
85 ** portions of the transformation chain:
86 **
87 ** functions observer transformation
88 **
89 ** eraApcg eraApcg13 geocentric ICRS <-> GCRS
90 ** eraApci eraApci13 terrestrial ICRS <-> CIRS
91 ** eraApco eraApco13 terrestrial ICRS <-> observed
92 ** eraApcs eraApcs13 space ICRS <-> GCRS
93 ** eraAper eraAper13 terrestrial update Earth rotation
94 ** eraApio eraApio13 terrestrial CIRS <-> observed
95 **
96 ** Those with names ending in "13" use contemporary ERFA models to
97 ** compute the various ephemerides. The others accept ephemerides
98 ** supplied by the caller.
99 **
100 ** The transformation from ICRS to GCRS covers space motion,
101 ** parallax, light deflection, and aberration. From GCRS to CIRS
102 ** comprises frame bias and precession-nutation. From CIRS to
103 ** observed takes account of Earth rotation, polar motion, diurnal
104 ** aberration and parallax (unless subsumed into the ICRS <-> GCRS
105 ** transformation), and atmospheric refraction.
106 **
107 ** 6) The context structure astrom produced by this function is used by
108 ** eraAtciq* and eraAticq*.
109 **
110 ** Called:
111 ** eraEpv00 Earth position and velocity
112 ** eraApcs astrometry parameters, ICRS-GCRS, space observer
113 **
114 ** Copyright (C) 2013-2015, NumFOCUS Foundation.
115 ** Derived, with permission, from the SOFA library. See notes at end of file.
116 */
117 {
118  double ehpv[2][3], ebpv[2][3];
119 
120 /* Earth barycentric & heliocentric position/velocity (au, au/d). */
121  (void) eraEpv00(date1, date2, ehpv, ebpv);
122 
123 /* Compute the star-independent astrometry parameters. */
124  eraApcs(date1, date2, pv, ebpv, ehpv[0], astrom);
125 
126 /* Finished. */
127 
128 }
129 /*----------------------------------------------------------------------
130 **
131 **
132 ** Copyright (C) 2013-2015, NumFOCUS Foundation.
133 ** All rights reserved.
134 **
135 ** This library is derived, with permission, from the International
136 ** Astronomical Union's "Standards of Fundamental Astronomy" library,
137 ** available from http://www.iausofa.org.
138 **
139 ** The ERFA version is intended to retain identical functionality to
140 ** the SOFA library, but made distinct through different function and
141 ** file names, as set out in the SOFA license conditions. The SOFA
142 ** original has a role as a reference standard for the IAU and IERS,
143 ** and consequently redistribution is permitted only in its unaltered
144 ** state. The ERFA version is not subject to this restriction and
145 ** therefore can be included in distributions which do not support the
146 ** concept of "read only" software.
147 **
148 ** Although the intent is to replicate the SOFA API (other than
149 ** replacement of prefix names) and results (with the exception of
150 ** bugs; any that are discovered will be fixed), SOFA is not
151 ** responsible for any errors found in this version of the library.
152 **
153 ** If you wish to acknowledge the SOFA heritage, please acknowledge
154 ** that you are using a library derived from SOFA, rather than SOFA
155 ** itself.
156 **
157 **
158 ** TERMS AND CONDITIONS
159 **
160 ** Redistribution and use in source and binary forms, with or without
161 ** modification, are permitted provided that the following conditions
162 ** are met:
163 **
164 ** 1 Redistributions of source code must retain the above copyright
165 ** notice, this list of conditions and the following disclaimer.
166 **
167 ** 2 Redistributions in binary form must reproduce the above copyright
168 ** notice, this list of conditions and the following disclaimer in
169 ** the documentation and/or other materials provided with the
170 ** distribution.
171 **
172 ** 3 Neither the name of the Standards Of Fundamental Astronomy Board,
173 ** the International Astronomical Union nor the names of its
174 ** contributors may be used to endorse or promote products derived
175 ** from this software without specific prior written permission.
176 **
177 ** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
178 ** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
179 ** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
180 ** FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
181 ** COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
182 ** INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
183 ** BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
184 ** LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
185 ** CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
186 ** LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
187 ** ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
188 ** POSSIBILITY OF SUCH DAMAGE.
189 **
190 */
eraApcs
void eraApcs(double date1, double date2, double pv[2][3], double ebpv[2][3], double ehp[3], eraASTROM *astrom)
Definition: apcs.c:3
eraEpv00
int eraEpv00(double date1, double date2, double pvh[2][3], double pvb[2][3])
Definition: epv00.c:3
eraApcs13
void eraApcs13(double date1, double date2, double pv[2][3], eraASTROM *astrom)
Definition: apcs13.c:3