source: trunk/FACT++/erfa/src/apco13.c@ 18348

Last change on this file since 18348 was 18348, checked in by tbretz, 9 years ago
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1#include "erfa.h"
2
3int eraApco13(double utc1, double utc2, double dut1,
4 double elong, double phi, double hm, double xp, double yp,
5 double phpa, double tc, double rh, double wl,
6 eraASTROM *astrom, double *eo)
7/*
8** - - - - - - - - - -
9** e r a A p c o 1 3
10** - - - - - - - - - -
11**
12** For a terrestrial observer, prepare star-independent astrometry
13** parameters for transformations between ICRS and observed
14** coordinates. The caller supplies UTC, site coordinates, ambient air
15** conditions and observing wavelength, and ERFA models are used to
16** obtain the Earth ephemeris, CIP/CIO and refraction constants.
17**
18** The parameters produced by this function are required in the
19** parallax, light deflection, aberration, and bias-precession-nutation
20** parts of the ICRS/CIRS transformations.
21**
22** Given:
23** utc1 double UTC as a 2-part...
24** utc2 double ...quasi Julian Date (Notes 1,2)
25** dut1 double UT1-UTC (seconds, Note 3)
26** elong double longitude (radians, east +ve, Note 4)
27** phi double latitude (geodetic, radians, Note 4)
28** hm double height above ellipsoid (m, geodetic, Notes 4,6)
29** xp,yp double polar motion coordinates (radians, Note 5)
30** phpa double pressure at the observer (hPa = mB, Note 6)
31** tc double ambient temperature at the observer (deg C)
32** rh double relative humidity at the observer (range 0-1)
33** wl double wavelength (micrometers, Note 7)
34**
35** Returned:
36** astrom eraASTROM* star-independent astrometry parameters:
37** pmt double PM time interval (SSB, Julian years)
38** eb double[3] SSB to observer (vector, au)
39** eh double[3] Sun to observer (unit vector)
40** em double distance from Sun to observer (au)
41** v double[3] barycentric observer velocity (vector, c)
42** bm1 double sqrt(1-|v|^2): reciprocal of Lorenz factor
43** bpn double[3][3] bias-precession-nutation matrix
44** along double longitude + s' (radians)
45** xpl double polar motion xp wrt local meridian (radians)
46** ypl double polar motion yp wrt local meridian (radians)
47** sphi double sine of geodetic latitude
48** cphi double cosine of geodetic latitude
49** diurab double magnitude of diurnal aberration vector
50** eral double "local" Earth rotation angle (radians)
51** refa double refraction constant A (radians)
52** refb double refraction constant B (radians)
53** eo double* equation of the origins (ERA-GST)
54**
55** Returned (function value):
56** int status: +1 = dubious year (Note 2)
57** 0 = OK
58** -1 = unacceptable date
59**
60** Notes:
61**
62** 1) utc1+utc2 is quasi Julian Date (see Note 2), apportioned in any
63** convenient way between the two arguments, for example where utc1
64** is the Julian Day Number and utc2 is the fraction of a day.
65**
66** However, JD cannot unambiguously represent UTC during a leap
67** second unless special measures are taken. The convention in the
68** present function is that the JD day represents UTC days whether
69** the length is 86399, 86400 or 86401 SI seconds.
70**
71** Applications should use the function eraDtf2d to convert from
72** calendar date and time of day into 2-part quasi Julian Date, as
73** it implements the leap-second-ambiguity convention just
74** described.
75**
76** 2) The warning status "dubious year" flags UTCs that predate the
77** introduction of the time scale or that are too far in the
78** future to be trusted. See eraDat for further details.
79**
80** 3) UT1-UTC is tabulated in IERS bulletins. It increases by exactly
81** one second at the end of each positive UTC leap second,
82** introduced in order to keep UT1-UTC within +/- 0.9s. n.b. This
83** practice is under review, and in the future UT1-UTC may grow
84** essentially without limit.
85**
86** 4) The geographical coordinates are with respect to the ERFA_WGS84
87** reference ellipsoid. TAKE CARE WITH THE LONGITUDE SIGN: the
88** longitude required by the present function is east-positive
89** (i.e. right-handed), in accordance with geographical convention.
90**
91** 5) The polar motion xp,yp can be obtained from IERS bulletins. The
92** values are the coordinates (in radians) of the Celestial
93** Intermediate Pole with respect to the International Terrestrial
94** Reference System (see IERS Conventions 2003), measured along the
95** meridians 0 and 90 deg west respectively. For many
96** applications, xp and yp can be set to zero.
97**
98** Internally, the polar motion is stored in a form rotated onto
99** the local meridian.
100**
101** 6) If hm, the height above the ellipsoid of the observing station
102** in meters, is not known but phpa, the pressure in hPa (=mB), is
103** available, an adequate estimate of hm can be obtained from the
104** expression
105**
106** hm = -29.3 * tsl * log ( phpa / 1013.25 );
107**
108** where tsl is the approximate sea-level air temperature in K
109** (See Astrophysical Quantities, C.W.Allen, 3rd edition, section
110** 52). Similarly, if the pressure phpa is not known, it can be
111** estimated from the height of the observing station, hm, as
112** follows:
113**
114** phpa = 1013.25 * exp ( -hm / ( 29.3 * tsl ) );
115**
116** Note, however, that the refraction is nearly proportional to
117** the pressure and that an accurate phpa value is important for
118** precise work.
119**
120** 7) The argument wl specifies the observing wavelength in
121** micrometers. The transition from optical to radio is assumed to
122** occur at 100 micrometers (about 3000 GHz).
123**
124** 8) It is advisable to take great care with units, as even unlikely
125** values of the input parameters are accepted and processed in
126** accordance with the models used.
127**
128** 9) In cases where the caller wishes to supply his own Earth
129** ephemeris, Earth rotation information and refraction constants,
130** the function eraApco can be used instead of the present function.
131**
132** 10) This is one of several functions that inserts into the astrom
133** structure star-independent parameters needed for the chain of
134** astrometric transformations ICRS <-> GCRS <-> CIRS <-> observed.
135**
136** The various functions support different classes of observer and
137** portions of the transformation chain:
138**
139** functions observer transformation
140**
141** eraApcg eraApcg13 geocentric ICRS <-> GCRS
142** eraApci eraApci13 terrestrial ICRS <-> CIRS
143** eraApco eraApco13 terrestrial ICRS <-> observed
144** eraApcs eraApcs13 space ICRS <-> GCRS
145** eraAper eraAper13 terrestrial update Earth rotation
146** eraApio eraApio13 terrestrial CIRS <-> observed
147**
148** Those with names ending in "13" use contemporary ERFA models to
149** compute the various ephemerides. The others accept ephemerides
150** supplied by the caller.
151**
152** The transformation from ICRS to GCRS covers space motion,
153** parallax, light deflection, and aberration. From GCRS to CIRS
154** comprises frame bias and precession-nutation. From CIRS to
155** observed takes account of Earth rotation, polar motion, diurnal
156** aberration and parallax (unless subsumed into the ICRS <-> GCRS
157** transformation), and atmospheric refraction.
158**
159** 11) The context structure astrom produced by this function is used
160** by eraAtioq, eraAtoiq, eraAtciq* and eraAticq*.
161**
162** Called:
163** eraUtctai UTC to TAI
164** eraTaitt TAI to TT
165** eraUtcut1 UTC to UT1
166** eraEpv00 Earth position and velocity
167** eraPnm06a classical NPB matrix, IAU 2006/2000A
168** eraBpn2xy extract CIP X,Y coordinates from NPB matrix
169** eraS06 the CIO locator s, given X,Y, IAU 2006
170** eraEra00 Earth rotation angle, IAU 2000
171** eraSp00 the TIO locator s', IERS 2000
172** eraRefco refraction constants for given ambient conditions
173** eraApco astrometry parameters, ICRS-observed
174** eraEors equation of the origins, given NPB matrix and s
175**
176** Copyright (C) 2013-2015, NumFOCUS Foundation.
177** Derived, with permission, from the SOFA library. See notes at end of file.
178*/
179{
180 int j;
181 double tai1, tai2, tt1, tt2, ut11, ut12, ehpv[2][3], ebpv[2][3],
182 r[3][3], x, y, s, theta, sp, refa, refb;
183
184/* UTC to other time scales. */
185 j = eraUtctai(utc1, utc2, &tai1, &tai2);
186 if ( j < 0 ) return -1;
187 j = eraTaitt(tai1, tai2, &tt1, &tt2);
188 j = eraUtcut1(utc1, utc2, dut1, &ut11, &ut12);
189 if ( j < 0 ) return -1;
190
191/* Earth barycentric & heliocentric position/velocity (au, au/d). */
192 (void) eraEpv00(tt1, tt2, ehpv, ebpv);
193
194/* Form the equinox based BPN matrix, IAU 2006/2000A. */
195 eraPnm06a(tt1, tt2, r);
196
197/* Extract CIP X,Y. */
198 eraBpn2xy(r, &x, &y);
199
200/* Obtain CIO locator s. */
201 s = eraS06(tt1, tt2, x, y);
202
203/* Earth rotation angle. */
204 theta = eraEra00(ut11, ut12);
205
206/* TIO locator s'. */
207 sp = eraSp00(tt1, tt2);
208
209/* Refraction constants A and B. */
210 eraRefco(phpa, tc, rh, wl, &refa, &refb);
211
212/* Compute the star-independent astrometry parameters. */
213 eraApco(tt1, tt2, ebpv, ehpv[0], x, y, s, theta,
214 elong, phi, hm, xp, yp, sp, refa, refb, astrom);
215
216/* Equation of the origins. */
217 *eo = eraEors(r, s);
218
219/* Return any warning status. */
220 return j;
221
222/* Finished. */
223
224}
225/*----------------------------------------------------------------------
226**
227**
228** Copyright (C) 2013-2015, NumFOCUS Foundation.
229** All rights reserved.
230**
231** This library is derived, with permission, from the International
232** Astronomical Union's "Standards of Fundamental Astronomy" library,
233** available from http://www.iausofa.org.
234**
235** The ERFA version is intended to retain identical functionality to
236** the SOFA library, but made distinct through different function and
237** file names, as set out in the SOFA license conditions. The SOFA
238** original has a role as a reference standard for the IAU and IERS,
239** and consequently redistribution is permitted only in its unaltered
240** state. The ERFA version is not subject to this restriction and
241** therefore can be included in distributions which do not support the
242** concept of "read only" software.
243**
244** Although the intent is to replicate the SOFA API (other than
245** replacement of prefix names) and results (with the exception of
246** bugs; any that are discovered will be fixed), SOFA is not
247** responsible for any errors found in this version of the library.
248**
249** If you wish to acknowledge the SOFA heritage, please acknowledge
250** that you are using a library derived from SOFA, rather than SOFA
251** itself.
252**
253**
254** TERMS AND CONDITIONS
255**
256** Redistribution and use in source and binary forms, with or without
257** modification, are permitted provided that the following conditions
258** are met:
259**
260** 1 Redistributions of source code must retain the above copyright
261** notice, this list of conditions and the following disclaimer.
262**
263** 2 Redistributions in binary form must reproduce the above copyright
264** notice, this list of conditions and the following disclaimer in
265** the documentation and/or other materials provided with the
266** distribution.
267**
268** 3 Neither the name of the Standards Of Fundamental Astronomy Board,
269** the International Astronomical Union nor the names of its
270** contributors may be used to endorse or promote products derived
271** from this software without specific prior written permission.
272**
273** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
274** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
275** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
276** FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
277** COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
278** INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
279** BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
280** LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
281** CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
282** LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
283** ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
284** POSSIBILITY OF SUCH DAMAGE.
285**
286*/
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