source: trunk/FACT++/erfa/src/atco13.c@ 19496

Last change on this file since 19496 was 18921, checked in by tbretz, 7 years ago
Updated to ERFA 1.4.0
File size: 10.8 KB
Line 
1#include "erfa.h"
2
3int eraAtco13(double rc, double dc,
4 double pr, double pd, double px, double rv,
5 double utc1, double utc2, double dut1,
6 double elong, double phi, double hm, double xp, double yp,
7 double phpa, double tc, double rh, double wl,
8 double *aob, double *zob, double *hob,
9 double *dob, double *rob, double *eo)
10/*
11** - - - - - - - - - -
12** e r a A t c o 1 3
13** - - - - - - - - - -
14**
15** ICRS RA,Dec to observed place. The caller supplies UTC, site
16** coordinates, ambient air conditions and observing wavelength.
17**
18** ERFA models are used for the Earth ephemeris, bias-precession-
19** nutation, Earth orientation and refraction.
20**
21** Given:
22** rc,dc double ICRS right ascension at J2000.0 (radians, Note 1)
23** pr double RA proper motion (radians/year; Note 2)
24** pd double Dec proper motion (radians/year)
25** px double parallax (arcsec)
26** rv double radial velocity (km/s, +ve if receding)
27** utc1 double UTC as a 2-part...
28** utc2 double ...quasi Julian Date (Notes 3-4)
29** dut1 double UT1-UTC (seconds, Note 5)
30** elong double longitude (radians, east +ve, Note 6)
31** phi double latitude (geodetic, radians, Note 6)
32** hm double height above ellipsoid (m, geodetic, Notes 6,8)
33** xp,yp double polar motion coordinates (radians, Note 7)
34** phpa double pressure at the observer (hPa = mB, Note 8)
35** tc double ambient temperature at the observer (deg C)
36** rh double relative humidity at the observer (range 0-1)
37** wl double wavelength (micrometers, Note 9)
38**
39** Returned:
40** aob double* observed azimuth (radians: N=0,E=90)
41** zob double* observed zenith distance (radians)
42** hob double* observed hour angle (radians)
43** dob double* observed declination (radians)
44** rob double* observed right ascension (CIO-based, radians)
45** eo double* equation of the origins (ERA-GST)
46**
47** Returned (function value):
48** int status: +1 = dubious year (Note 4)
49** 0 = OK
50** -1 = unacceptable date
51**
52** Notes:
53**
54** 1) Star data for an epoch other than J2000.0 (for example from the
55** Hipparcos catalog, which has an epoch of J1991.25) will require
56** a preliminary call to eraPmsafe before use.
57**
58** 2) The proper motion in RA is dRA/dt rather than cos(Dec)*dRA/dt.
59**
60** 3) utc1+utc2 is quasi Julian Date (see Note 2), apportioned in any
61** convenient way between the two arguments, for example where utc1
62** is the Julian Day Number and utc2 is the fraction of a day.
63**
64** However, JD cannot unambiguously represent UTC during a leap
65** second unless special measures are taken. The convention in the
66** present function is that the JD day represents UTC days whether
67** the length is 86399, 86400 or 86401 SI seconds.
68**
69** Applications should use the function eraDtf2d to convert from
70** calendar date and time of day into 2-part quasi Julian Date, as
71** it implements the leap-second-ambiguity convention just
72** described.
73**
74** 4) The warning status "dubious year" flags UTCs that predate the
75** introduction of the time scale or that are too far in the
76** future to be trusted. See eraDat for further details.
77**
78** 5) UT1-UTC is tabulated in IERS bulletins. It increases by exactly
79** one second at the end of each positive UTC leap second,
80** introduced in order to keep UT1-UTC within +/- 0.9s. n.b. This
81** practice is under review, and in the future UT1-UTC may grow
82** essentially without limit.
83**
84** 6) The geographical coordinates are with respect to the ERFA_WGS84
85** reference ellipsoid. TAKE CARE WITH THE LONGITUDE SIGN: the
86** longitude required by the present function is east-positive
87** (i.e. right-handed), in accordance with geographical convention.
88**
89** 7) The polar motion xp,yp can be obtained from IERS bulletins. The
90** values are the coordinates (in radians) of the Celestial
91** Intermediate Pole with respect to the International Terrestrial
92** Reference System (see IERS Conventions 2003), measured along the
93** meridians 0 and 90 deg west respectively. For many
94** applications, xp and yp can be set to zero.
95**
96** 8) If hm, the height above the ellipsoid of the observing station
97** in meters, is not known but phpa, the pressure in hPa (=mB),
98** is available, an adequate estimate of hm can be obtained from
99** the expression
100**
101** hm = -29.3 * tsl * log ( phpa / 1013.25 );
102**
103** where tsl is the approximate sea-level air temperature in K
104** (See Astrophysical Quantities, C.W.Allen, 3rd edition, section
105** 52). Similarly, if the pressure phpa is not known, it can be
106** estimated from the height of the observing station, hm, as
107** follows:
108**
109** phpa = 1013.25 * exp ( -hm / ( 29.3 * tsl ) );
110**
111** Note, however, that the refraction is nearly proportional to
112** the pressure and that an accurate phpa value is important for
113** precise work.
114**
115** 9) The argument wl specifies the observing wavelength in
116** micrometers. The transition from optical to radio is assumed to
117** occur at 100 micrometers (about 3000 GHz).
118**
119** 10) The accuracy of the result is limited by the corrections for
120** refraction, which use a simple A*tan(z) + B*tan^3(z) model.
121** Providing the meteorological parameters are known accurately and
122** there are no gross local effects, the predicted observed
123** coordinates should be within 0.05 arcsec (optical) or 1 arcsec
124** (radio) for a zenith distance of less than 70 degrees, better
125** than 30 arcsec (optical or radio) at 85 degrees and better
126** than 20 arcmin (optical) or 30 arcmin (radio) at the horizon.
127**
128** Without refraction, the complementary functions eraAtco13 and
129** eraAtoc13 are self-consistent to better than 1 microarcsecond
130** all over the celestial sphere. With refraction included,
131** consistency falls off at high zenith distances, but is still
132** better than 0.05 arcsec at 85 degrees.
133**
134** 11) "Observed" Az,ZD means the position that would be seen by a
135** perfect geodetically aligned theodolite. (Zenith distance is
136** used rather than altitude in order to reflect the fact that no
137** allowance is made for depression of the horizon.) This is
138** related to the observed HA,Dec via the standard rotation, using
139** the geodetic latitude (corrected for polar motion), while the
140** observed HA and RA are related simply through the Earth rotation
141** angle and the site longitude. "Observed" RA,Dec or HA,Dec thus
142** means the position that would be seen by a perfect equatorial
143** with its polar axis aligned to the Earth's axis of rotation.
144**
145** 12) It is advisable to take great care with units, as even unlikely
146** values of the input parameters are accepted and processed in
147** accordance with the models used.
148**
149** Called:
150** eraApco13 astrometry parameters, ICRS-observed, 2013
151** eraAtciq quick ICRS to CIRS
152** eraAtioq quick CIRS to observed
153**
154** Copyright (C) 2013-2017, NumFOCUS Foundation.
155** Derived, with permission, from the SOFA library. See notes at end of file.
156*/
157{
158 int j;
159 eraASTROM astrom;
160 double ri, di;
161
162
163/* Star-independent astrometry parameters. */
164 j = eraApco13(utc1, utc2, dut1, elong, phi, hm, xp, yp,
165 phpa, tc, rh, wl, &astrom, eo);
166
167/* Abort if bad UTC. */
168 if ( j < 0 ) return j;
169
170/* Transform ICRS to CIRS. */
171 eraAtciq(rc, dc, pr, pd, px, rv, &astrom, &ri, &di);
172
173/* Transform CIRS to observed. */
174 eraAtioq(ri, di, &astrom, aob, zob, hob, dob, rob);
175
176/* Return OK/warning status. */
177 return j;
178
179/* Finished. */
180
181}
182/*----------------------------------------------------------------------
183**
184**
185** Copyright (C) 2013-2017, NumFOCUS Foundation.
186** All rights reserved.
187**
188** This library is derived, with permission, from the International
189** Astronomical Union's "Standards of Fundamental Astronomy" library,
190** available from http://www.iausofa.org.
191**
192** The ERFA version is intended to retain identical functionality to
193** the SOFA library, but made distinct through different function and
194** file names, as set out in the SOFA license conditions. The SOFA
195** original has a role as a reference standard for the IAU and IERS,
196** and consequently redistribution is permitted only in its unaltered
197** state. The ERFA version is not subject to this restriction and
198** therefore can be included in distributions which do not support the
199** concept of "read only" software.
200**
201** Although the intent is to replicate the SOFA API (other than
202** replacement of prefix names) and results (with the exception of
203** bugs; any that are discovered will be fixed), SOFA is not
204** responsible for any errors found in this version of the library.
205**
206** If you wish to acknowledge the SOFA heritage, please acknowledge
207** that you are using a library derived from SOFA, rather than SOFA
208** itself.
209**
210**
211** TERMS AND CONDITIONS
212**
213** Redistribution and use in source and binary forms, with or without
214** modification, are permitted provided that the following conditions
215** are met:
216**
217** 1 Redistributions of source code must retain the above copyright
218** notice, this list of conditions and the following disclaimer.
219**
220** 2 Redistributions in binary form must reproduce the above copyright
221** notice, this list of conditions and the following disclaimer in
222** the documentation and/or other materials provided with the
223** distribution.
224**
225** 3 Neither the name of the Standards Of Fundamental Astronomy Board,
226** the International Astronomical Union nor the names of its
227** contributors may be used to endorse or promote products derived
228** from this software without specific prior written permission.
229**
230** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
231** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
232** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
233** FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
234** COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
235** INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
236** BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
237** LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
238** CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
239** LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
240** ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
241** POSSIBILITY OF SUCH DAMAGE.
242**
243*/
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