FACT++  1.0
ab.c
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1 #include "erfa.h"
2 
3 void eraAb(double pnat[3], double v[3], double s, double bm1,
4  double ppr[3])
5 /*
6 ** - - - - - -
7 ** e r a A b
8 ** - - - - - -
9 **
10 ** Apply aberration to transform natural direction into proper
11 ** direction.
12 **
13 ** Given:
14 ** pnat double[3] natural direction to the source (unit vector)
15 ** v double[3] observer barycentric velocity in units of c
16 ** s double distance between the Sun and the observer (au)
17 ** bm1 double sqrt(1-|v|^2): reciprocal of Lorenz factor
18 **
19 ** Returned:
20 ** ppr double[3] proper direction to source (unit vector)
21 **
22 ** Notes:
23 **
24 ** 1) The algorithm is based on Expr. (7.40) in the Explanatory
25 ** Supplement (Urban & Seidelmann 2013), but with the following
26 ** changes:
27 **
28 ** o Rigorous rather than approximate normalization is applied.
29 **
30 ** o The gravitational potential term from Expr. (7) in
31 ** Klioner (2003) is added, taking into account only the Sun's
32 ** contribution. This has a maximum effect of about
33 ** 0.4 microarcsecond.
34 **
35 ** 2) In almost all cases, the maximum accuracy will be limited by the
36 ** supplied velocity. For example, if the ERFA eraEpv00 function is
37 ** used, errors of up to 5 microarcseconds could occur.
38 **
39 ** References:
40 **
41 ** Urban, S. & Seidelmann, P. K. (eds), Explanatory Supplement to
42 ** the Astronomical Almanac, 3rd ed., University Science Books
43 ** (2013).
44 **
45 ** Klioner, Sergei A., "A practical relativistic model for micro-
46 ** arcsecond astrometry in space", Astr. J. 125, 1580-1597 (2003).
47 **
48 ** Called:
49 ** eraPdp scalar product of two p-vectors
50 **
51 ** Copyright (C) 2013-2015, NumFOCUS Foundation.
52 ** Derived, with permission, from the SOFA library. See notes at end of file.
53 */
54 {
55  int i;
56  double pdv, w1, w2, r2, w, p[3], r;
57 
58  pdv = eraPdp(pnat, v);
59  w1 = 1.0 + pdv/(1.0 + bm1);
60  w2 = ERFA_SRS/s;
61  r2 = 0.0;
62  for (i = 0; i < 3; i++) {
63  w = pnat[i]*bm1 + w1*v[i] + w2*(v[i] - pdv*pnat[i]);
64  p[i] = w;
65  r2 = r2 + w*w;
66  }
67  r = sqrt(r2);
68  for (i = 0; i < 3; i++) {
69  ppr[i] = p[i]/r;
70  }
71 
72 /* Finished. */
73 
74 }
75 /*----------------------------------------------------------------------
76 **
77 **
78 ** Copyright (C) 2013-2015, NumFOCUS Foundation.
79 ** All rights reserved.
80 **
81 ** This library is derived, with permission, from the International
82 ** Astronomical Union's "Standards of Fundamental Astronomy" library,
83 ** available from http://www.iausofa.org.
84 **
85 ** The ERFA version is intended to retain identical functionality to
86 ** the SOFA library, but made distinct through different function and
87 ** file names, as set out in the SOFA license conditions. The SOFA
88 ** original has a role as a reference standard for the IAU and IERS,
89 ** and consequently redistribution is permitted only in its unaltered
90 ** state. The ERFA version is not subject to this restriction and
91 ** therefore can be included in distributions which do not support the
92 ** concept of "read only" software.
93 **
94 ** Although the intent is to replicate the SOFA API (other than
95 ** replacement of prefix names) and results (with the exception of
96 ** bugs; any that are discovered will be fixed), SOFA is not
97 ** responsible for any errors found in this version of the library.
98 **
99 ** If you wish to acknowledge the SOFA heritage, please acknowledge
100 ** that you are using a library derived from SOFA, rather than SOFA
101 ** itself.
102 **
103 **
104 ** TERMS AND CONDITIONS
105 **
106 ** Redistribution and use in source and binary forms, with or without
107 ** modification, are permitted provided that the following conditions
108 ** are met:
109 **
110 ** 1 Redistributions of source code must retain the above copyright
111 ** notice, this list of conditions and the following disclaimer.
112 **
113 ** 2 Redistributions in binary form must reproduce the above copyright
114 ** notice, this list of conditions and the following disclaimer in
115 ** the documentation and/or other materials provided with the
116 ** distribution.
117 **
118 ** 3 Neither the name of the Standards Of Fundamental Astronomy Board,
119 ** the International Astronomical Union nor the names of its
120 ** contributors may be used to endorse or promote products derived
121 ** from this software without specific prior written permission.
122 **
123 ** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
124 ** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
125 ** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
126 ** FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
127 ** COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
128 ** INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
129 ** BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
130 ** LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
131 ** CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
132 ** LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
133 ** ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
134 ** POSSIBILITY OF SUCH DAMAGE.
135 **
136 */
eraPdp
double eraPdp(double a[3], double b[3])
Definition: pdp.c:3
eraAb
void eraAb(double pnat[3], double v[3], double s, double bm1, double ppr[3])
Definition: ab.c:3
ERFA_SRS
#define ERFA_SRS
Definition: erfam.h:122
i
int i
Definition: db_dim_client.c:21