File Coverage

erfasrc/src/icrs2g.c
Criterion Covered Total %
statement 0 8 0.0
branch n/a
condition n/a
subroutine n/a
pod n/a
total 0 8 0.0


line stmt bran cond sub pod time code
1             #include "erfa.h"
2              
3 0           void eraIcrs2g ( double dr, double dd, double *dl, double *db )
4             /*
5             ** - - - - - - - - - -
6             ** e r a I c r s 2 g
7             ** - - - - - - - - - -
8             **
9             ** Transformation from ICRS to Galactic Coordinates.
10             **
11             ** Given:
12             ** dr double ICRS right ascension (radians)
13             ** dd double ICRS declination (radians)
14             **
15             ** Returned:
16             ** dl double galactic longitude (radians)
17             ** db double galactic latitude (radians)
18             **
19             ** Notes:
20             **
21             ** 1) The IAU 1958 system of Galactic coordinates was defined with
22             ** respect to the now obsolete reference system FK4 B1950.0. When
23             ** interpreting the system in a modern context, several factors have
24             ** to be taken into account:
25             **
26             ** . The inclusion in FK4 positions of the E-terms of aberration.
27             **
28             ** . The distortion of the FK4 proper motion system by differential
29             ** Galactic rotation.
30             **
31             ** . The use of the B1950.0 equinox rather than the now-standard
32             ** J2000.0.
33             **
34             ** . The frame bias between ICRS and the J2000.0 mean place system.
35             **
36             ** The Hipparcos Catalogue (Perryman & ESA 1997) provides a rotation
37             ** matrix that transforms directly between ICRS and Galactic
38             ** coordinates with the above factors taken into account. The
39             ** matrix is derived from three angles, namely the ICRS coordinates
40             ** of the Galactic pole and the longitude of the ascending node of
41             ** the galactic equator on the ICRS equator. They are given in
42             ** degrees to five decimal places and for canonical purposes are
43             ** regarded as exact. In the Hipparcos Catalogue the matrix
44             ** elements are given to 10 decimal places (about 20 microarcsec).
45             ** In the present ERFA function the matrix elements have been
46             ** recomputed from the canonical three angles and are given to 30
47             ** decimal places.
48             **
49             ** 2) The inverse transformation is performed by the function eraG2icrs.
50             **
51             ** Called:
52             ** eraAnp normalize angle into range 0 to 2pi
53             ** eraAnpm normalize angle into range +/- pi
54             ** eraS2c spherical coordinates to unit vector
55             ** eraRxp product of r-matrix and p-vector
56             ** eraC2s p-vector to spherical
57             **
58             ** Reference:
59             ** Perryman M.A.C. & ESA, 1997, ESA SP-1200, The Hipparcos and Tycho
60             ** catalogues. Astrometric and photometric star catalogues
61             ** derived from the ESA Hipparcos Space Astrometry Mission. ESA
62             ** Publications Division, Noordwijk, Netherlands.
63             **
64             ** Copyright (C) 2013-2020, NumFOCUS Foundation.
65             ** Derived, with permission, from the SOFA library. See notes at end of file.
66             */
67             {
68             double v1[3], v2[3];
69              
70             /*
71             ** L2,B2 system of galactic coordinates in the form presented in the
72             ** Hipparcos Catalogue. In degrees:
73             **
74             ** P = 192.85948 right ascension of the Galactic north pole in ICRS
75             ** Q = 27.12825 declination of the Galactic north pole in ICRS
76             ** R = 32.93192 longitude of the ascending node of the Galactic
77             ** plane on the ICRS equator
78             **
79             ** ICRS to galactic rotation matrix, obtained by computing
80             ** R_3(-R) R_1(pi/2-Q) R_3(pi/2+P) to the full precision shown:
81             */
82 0           double r[3][3] = { { -0.054875560416215368492398900454,
83             -0.873437090234885048760383168409,
84             -0.483835015548713226831774175116 },
85             { +0.494109427875583673525222371358,
86             -0.444829629960011178146614061616,
87             +0.746982244497218890527388004556 },
88             { -0.867666149019004701181616534570,
89             -0.198076373431201528180486091412,
90             +0.455983776175066922272100478348 } };
91              
92              
93             /* Spherical to Cartesian. */
94 0           eraS2c(dr, dd, v1);
95              
96             /* ICRS to Galactic. */
97 0           eraRxp(r, v1, v2);
98              
99             /* Cartesian to spherical. */
100 0           eraC2s(v2, dl, db);
101              
102             /* Express in conventional ranges. */
103 0           *dl = eraAnp(*dl);
104 0           *db = eraAnpm(*db);
105              
106             /* Finished. */
107              
108 0           }
109             /*----------------------------------------------------------------------
110             **
111             **
112             ** Copyright (C) 2013-2020, NumFOCUS Foundation.
113             ** All rights reserved.
114             **
115             ** This library is derived, with permission, from the International
116             ** Astronomical Union's "Standards of Fundamental Astronomy" library,
117             ** available from http://www.iausofa.org.
118             **
119             ** The ERFA version is intended to retain identical functionality to
120             ** the SOFA library, but made distinct through different function and
121             ** file names, as set out in the SOFA license conditions. The SOFA
122             ** original has a role as a reference standard for the IAU and IERS,
123             ** and consequently redistribution is permitted only in its unaltered
124             ** state. The ERFA version is not subject to this restriction and
125             ** therefore can be included in distributions which do not support the
126             ** concept of "read only" software.
127             **
128             ** Although the intent is to replicate the SOFA API (other than
129             ** replacement of prefix names) and results (with the exception of
130             ** bugs; any that are discovered will be fixed), SOFA is not
131             ** responsible for any errors found in this version of the library.
132             **
133             ** If you wish to acknowledge the SOFA heritage, please acknowledge
134             ** that you are using a library derived from SOFA, rather than SOFA
135             ** itself.
136             **
137             **
138             ** TERMS AND CONDITIONS
139             **
140             ** Redistribution and use in source and binary forms, with or without
141             ** modification, are permitted provided that the following conditions
142             ** are met:
143             **
144             ** 1 Redistributions of source code must retain the above copyright
145             ** notice, this list of conditions and the following disclaimer.
146             **
147             ** 2 Redistributions in binary form must reproduce the above copyright
148             ** notice, this list of conditions and the following disclaimer in
149             ** the documentation and/or other materials provided with the
150             ** distribution.
151             **
152             ** 3 Neither the name of the Standards Of Fundamental Astronomy Board,
153             ** the International Astronomical Union nor the names of its
154             ** contributors may be used to endorse or promote products derived
155             ** from this software without specific prior written permission.
156             **
157             ** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
158             ** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
159             ** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
160             ** FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
161             ** COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
162             ** INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
163             ** BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
164             ** LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
165             ** CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
166             ** LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
167             ** ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
168             ** POSSIBILITY OF SUCH DAMAGE.
169             **
170             */