1 #include "erfa.h"
2 #include "erfam.h"
3
eraApio(double sp,double theta,double elong,double phi,double hm,double xp,double yp,double refa,double refb,eraASTROM * astrom)4 void eraApio(double sp, double theta,
5 double elong, double phi, double hm, double xp, double yp,
6 double refa, double refb,
7 eraASTROM *astrom)
8 /*
9 ** - - - - - - - -
10 ** e r a A p i o
11 ** - - - - - - - -
12 **
13 ** For a terrestrial observer, prepare star-independent astrometry
14 ** parameters for transformations between CIRS and observed
15 ** coordinates. The caller supplies the Earth orientation information
16 ** and the refraction constants as well as the site coordinates.
17 **
18 ** Given:
19 ** sp double the TIO locator s' (radians, Note 1)
20 ** theta double Earth rotation angle (radians)
21 ** elong double longitude (radians, east +ve, Note 2)
22 ** phi double geodetic latitude (radians, Note 2)
23 ** hm double height above ellipsoid (m, geodetic Note 2)
24 ** xp,yp double polar motion coordinates (radians, Note 3)
25 ** refa double refraction constant A (radians, Note 4)
26 ** refb double refraction constant B (radians, Note 4)
27 **
28 ** Returned:
29 ** astrom eraASTROM* star-independent astrometry parameters:
30 ** pmt double unchanged
31 ** eb double[3] unchanged
32 ** eh double[3] unchanged
33 ** em double unchanged
34 ** v double[3] unchanged
35 ** bm1 double unchanged
36 ** bpn double[3][3] unchanged
37 ** along double adjusted longitude (radians)
38 ** xpl double polar motion xp wrt local meridian (radians)
39 ** ypl double polar motion yp wrt local meridian (radians)
40 ** sphi double sine of geodetic latitude
41 ** cphi double cosine of geodetic latitude
42 ** diurab double magnitude of diurnal aberration vector
43 ** eral double "local" Earth rotation angle (radians)
44 ** refa double refraction constant A (radians)
45 ** refb double refraction constant B (radians)
46 **
47 ** Notes:
48 **
49 ** 1) sp, the TIO locator s', is a tiny quantity needed only by the
50 ** most precise applications. It can either be set to zero or
51 ** predicted using the ERFA function eraSp00.
52 **
53 ** 2) The geographical coordinates are with respect to the ERFA_WGS84
54 ** reference ellipsoid. TAKE CARE WITH THE LONGITUDE SIGN: the
55 ** longitude required by the present function is east-positive
56 ** (i.e. right-handed), in accordance with geographical convention.
57 **
58 ** 3) The polar motion xp,yp can be obtained from IERS bulletins. The
59 ** values are the coordinates (in radians) of the Celestial
60 ** Intermediate Pole with respect to the International Terrestrial
61 ** Reference System (see IERS Conventions 2003), measured along the
62 ** meridians 0 and 90 deg west respectively. For many applications,
63 ** xp and yp can be set to zero.
64 **
65 ** Internally, the polar motion is stored in a form rotated onto the
66 ** local meridian.
67 **
68 ** 4) The refraction constants refa and refb are for use in a
69 ** dZ = A*tan(Z)+B*tan^3(Z) model, where Z is the observed
70 ** (i.e. refracted) zenith distance and dZ is the amount of
71 ** refraction.
72 **
73 ** 5) It is advisable to take great care with units, as even unlikely
74 ** values of the input parameters are accepted and processed in
75 ** accordance with the models used.
76 **
77 ** 6) In cases where the caller does not wish to provide the Earth
78 ** rotation information and refraction constants, the function
79 ** eraApio13 can be used instead of the present function. This
80 ** starts from UTC and weather readings etc. and computes suitable
81 ** values using other ERFA functions.
82 **
83 ** 7) This is one of several functions that inserts into the astrom
84 ** structure star-independent parameters needed for the chain of
85 ** astrometric transformations ICRS <-> GCRS <-> CIRS <-> observed.
86 **
87 ** The various functions support different classes of observer and
88 ** portions of the transformation chain:
89 **
90 ** functions observer transformation
91 **
92 ** eraApcg eraApcg13 geocentric ICRS <-> GCRS
93 ** eraApci eraApci13 terrestrial ICRS <-> CIRS
94 ** eraApco eraApco13 terrestrial ICRS <-> observed
95 ** eraApcs eraApcs13 space ICRS <-> GCRS
96 ** eraAper eraAper13 terrestrial update Earth rotation
97 ** eraApio eraApio13 terrestrial CIRS <-> observed
98 **
99 ** Those with names ending in "13" use contemporary ERFA models to
100 ** compute the various ephemerides. The others accept ephemerides
101 ** supplied by the caller.
102 **
103 ** The transformation from ICRS to GCRS covers space motion,
104 ** parallax, light deflection, and aberration. From GCRS to CIRS
105 ** comprises frame bias and precession-nutation. From CIRS to
106 ** observed takes account of Earth rotation, polar motion, diurnal
107 ** aberration and parallax (unless subsumed into the ICRS <-> GCRS
108 ** transformation), and atmospheric refraction.
109 **
110 ** 8) The context structure astrom produced by this function is used by
111 ** eraAtioq and eraAtoiq.
112 **
113 ** Called:
114 ** eraIr initialize r-matrix to identity
115 ** eraRz rotate around Z-axis
116 ** eraRy rotate around Y-axis
117 ** eraRx rotate around X-axis
118 ** eraAnpm normalize angle into range +/- pi
119 ** eraPvtob position/velocity of terrestrial station
120 **
121 ** This revision: 2021 February 24
122 **
123 ** Copyright (C) 2013-2021, NumFOCUS Foundation.
124 ** Derived, with permission, from the SOFA library. See notes at end of file.
125 */
126 {
127 double r[3][3], a, b, eral, c, pv[2][3];
128
129
130 /* Form the rotation matrix, CIRS to apparent [HA,Dec]. */
131 eraIr(r);
132 eraRz(theta+sp, r);
133 eraRy(-xp, r);
134 eraRx(-yp, r);
135 eraRz(elong, r);
136
137 /* Solve for local Earth rotation angle. */
138 a = r[0][0];
139 b = r[0][1];
140 eral = ( a != 0.0 || b != 0.0 ) ? atan2(b, a) : 0.0;
141 astrom->eral = eral;
142
143 /* Solve for polar motion [X,Y] with respect to local meridian. */
144 a = r[0][0];
145 c = r[0][2];
146 astrom->xpl = atan2(c, sqrt(a*a+b*b));
147 a = r[1][2];
148 b = r[2][2];
149 astrom->ypl = ( a != 0.0 || b != 0.0 ) ? -atan2(a, b) : 0.0;
150
151 /* Adjusted longitude. */
152 astrom->along = eraAnpm(eral - theta);
153
154 /* Functions of latitude. */
155 astrom->sphi = sin(phi);
156 astrom->cphi = cos(phi);
157
158 /* Observer's geocentric position and velocity (m, m/s, CIRS). */
159 eraPvtob(elong, phi, hm, xp, yp, sp, theta, pv);
160
161 /* Magnitude of diurnal aberration vector. */
162 astrom->diurab = sqrt(pv[1][0]*pv[1][0]+pv[1][1]*pv[1][1]) / ERFA_CMPS;
163
164 /* Refraction constants. */
165 astrom->refa = refa;
166 astrom->refb = refb;
167
168 /* Finished. */
169
170 }
171 /*----------------------------------------------------------------------
172 **
173 **
174 ** Copyright (C) 2013-2021, NumFOCUS Foundation.
175 ** All rights reserved.
176 **
177 ** This library is derived, with permission, from the International
178 ** Astronomical Union's "Standards of Fundamental Astronomy" library,
179 ** available from http://www.iausofa.org.
180 **
181 ** The ERFA version is intended to retain identical functionality to
182 ** the SOFA library, but made distinct through different function and
183 ** file names, as set out in the SOFA license conditions. The SOFA
184 ** original has a role as a reference standard for the IAU and IERS,
185 ** and consequently redistribution is permitted only in its unaltered
186 ** state. The ERFA version is not subject to this restriction and
187 ** therefore can be included in distributions which do not support the
188 ** concept of "read only" software.
189 **
190 ** Although the intent is to replicate the SOFA API (other than
191 ** replacement of prefix names) and results (with the exception of
192 ** bugs; any that are discovered will be fixed), SOFA is not
193 ** responsible for any errors found in this version of the library.
194 **
195 ** If you wish to acknowledge the SOFA heritage, please acknowledge
196 ** that you are using a library derived from SOFA, rather than SOFA
197 ** itself.
198 **
199 **
200 ** TERMS AND CONDITIONS
201 **
202 ** Redistribution and use in source and binary forms, with or without
203 ** modification, are permitted provided that the following conditions
204 ** are met:
205 **
206 ** 1 Redistributions of source code must retain the above copyright
207 ** notice, this list of conditions and the following disclaimer.
208 **
209 ** 2 Redistributions in binary form must reproduce the above copyright
210 ** notice, this list of conditions and the following disclaimer in
211 ** the documentation and/or other materials provided with the
212 ** distribution.
213 **
214 ** 3 Neither the name of the Standards Of Fundamental Astronomy Board,
215 ** the International Astronomical Union nor the names of its
216 ** contributors may be used to endorse or promote products derived
217 ** from this software without specific prior written permission.
218 **
219 ** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
220 ** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
221 ** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
222 ** FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
223 ** COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
224 ** INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
225 ** BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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231 **
232 */
233