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Diffstat (limited to 'ast/erfa/atio13.c')
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diff --git a/ast/erfa/atio13.c b/ast/erfa/atio13.c new file mode 100644 index 0000000..6201776 --- /dev/null +++ b/ast/erfa/atio13.c @@ -0,0 +1,222 @@ +#include "erfa.h" + +int eraAtio13(double ri, double di, + double utc1, double utc2, double dut1, + double elong, double phi, double hm, double xp, double yp, + double phpa, double tc, double rh, double wl, + double *aob, double *zob, double *hob, + double *dob, double *rob) +/* +** - - - - - - - - - - +** e r a A t i o 1 3 +** - - - - - - - - - - +** +** CIRS RA,Dec to observed place. The caller supplies UTC, site +** coordinates, ambient air conditions and observing wavelength. +** +** Given: +** ri double CIRS right ascension (CIO-based, radians) +** di double CIRS declination (radians) +** utc1 double UTC as a 2-part... +** utc2 double ...quasi Julian Date (Notes 1,2) +** dut1 double UT1-UTC (seconds, Note 3) +** elong double longitude (radians, east +ve, Note 4) +** phi double geodetic latitude (radians, Note 4) +** hm double height above ellipsoid (m, geodetic Notes 4,6) +** xp,yp double polar motion coordinates (radians, Note 5) +** phpa double pressure at the observer (hPa = mB, Note 6) +** tc double ambient temperature at the observer (deg C) +** rh double relative humidity at the observer (range 0-1) +** wl double wavelength (micrometers, Note 7) +** +** Returned: +** aob double* observed azimuth (radians: N=0,E=90) +** zob double* observed zenith distance (radians) +** hob double* observed hour angle (radians) +** dob double* observed declination (radians) +** rob double* observed right ascension (CIO-based, radians) +** +** Returned (function value): +** int status: +1 = dubious year (Note 2) +** 0 = OK +** -1 = unacceptable date +** +** Notes: +** +** 1) utc1+utc2 is quasi Julian Date (see Note 2), apportioned in any +** convenient way between the two arguments, for example where utc1 +** is the Julian Day Number and utc2 is the fraction of a day. +** +** However, JD cannot unambiguously represent UTC during a leap +** second unless special measures are taken. The convention in the +** present function is that the JD day represents UTC days whether +** the length is 86399, 86400 or 86401 SI seconds. +** +** Applications should use the function eraDtf2d to convert from +** calendar date and time of day into 2-part quasi Julian Date, as +** it implements the leap-second-ambiguity convention just +** described. +** +** 2) The warning status "dubious year" flags UTCs that predate the +** introduction of the time scale or that are too far in the +** future to be trusted. See eraDat for further details. +** +** 3) UT1-UTC is tabulated in IERS bulletins. It increases by exactly +** one second at the end of each positive UTC leap second, +** introduced in order to keep UT1-UTC within +/- 0.9s. n.b. This +** practice is under review, and in the future UT1-UTC may grow +** essentially without limit. +** +** 4) The geographical coordinates are with respect to the ERFA_WGS84 +** reference ellipsoid. TAKE CARE WITH THE LONGITUDE SIGN: the +** longitude required by the present function is east-positive +** (i.e. right-handed), in accordance with geographical convention. +** +** 5) The polar motion xp,yp can be obtained from IERS bulletins. The +** values are the coordinates (in radians) of the Celestial +** Intermediate Pole with respect to the International Terrestrial +** Reference System (see IERS Conventions 2003), measured along the +** meridians 0 and 90 deg west respectively. For many +** applications, xp and yp can be set to zero. +** +** 6) If hm, the height above the ellipsoid of the observing station +** in meters, is not known but phpa, the pressure in hPa (=mB), is +** available, an adequate estimate of hm can be obtained from the +** expression +** +** hm = -29.3 * tsl * log ( phpa / 1013.25 ); +** +** where tsl is the approximate sea-level air temperature in K +** (See Astrophysical Quantities, C.W.Allen, 3rd edition, section +** 52). Similarly, if the pressure phpa is not known, it can be +** estimated from the height of the observing station, hm, as +** follows: +** +** phpa = 1013.25 * exp ( -hm / ( 29.3 * tsl ) ); +** +** Note, however, that the refraction is nearly proportional to +** the pressure and that an accurate phpa value is important for +** precise work. +** +** 7) The argument wl specifies the observing wavelength in +** micrometers. The transition from optical to radio is assumed to +** occur at 100 micrometers (about 3000 GHz). +** +** 8) "Observed" Az,ZD means the position that would be seen by a +** perfect geodetically aligned theodolite. (Zenith distance is +** used rather than altitude in order to reflect the fact that no +** allowance is made for depression of the horizon.) This is +** related to the observed HA,Dec via the standard rotation, using +** the geodetic latitude (corrected for polar motion), while the +** observed HA and RA are related simply through the Earth rotation +** angle and the site longitude. "Observed" RA,Dec or HA,Dec thus +** means the position that would be seen by a perfect equatorial +** with its polar axis aligned to the Earth's axis of rotation. +** +** 9) The accuracy of the result is limited by the corrections for +** refraction, which use a simple A*tan(z) + B*tan^3(z) model. +** Providing the meteorological parameters are known accurately and +** there are no gross local effects, the predicted astrometric +** coordinates should be within 0.05 arcsec (optical) or 1 arcsec +** (radio) for a zenith distance of less than 70 degrees, better +** than 30 arcsec (optical or radio) at 85 degrees and better +** than 20 arcmin (optical) or 30 arcmin (radio) at the horizon. +** +** 10) The complementary functions eraAtio13 and eraAtoi13 are self- +** consistent to better than 1 microarcsecond all over the +** celestial sphere. +** +** 11) It is advisable to take great care with units, as even unlikely +** values of the input parameters are accepted and processed in +** accordance with the models used. +** +** Called: +** eraApio13 astrometry parameters, CIRS-observed, 2013 +** eraAtioq quick CIRS to observed +** +** Copyright (C) 2013-2016, NumFOCUS Foundation. +** Derived, with permission, from the SOFA library. See notes at end of file. +*/ +{ + int j; + eraASTROM astrom; + + +/* Star-independent astrometry parameters for CIRS->observed. */ + j = eraApio13(utc1, utc2, dut1, elong, phi, hm, xp, yp, + phpa, tc, rh, wl, &astrom); + +/* Abort if bad UTC. */ + if ( j < 0 ) return j; + +/* Transform CIRS to observed. */ + eraAtioq(ri, di, &astrom, aob, zob, hob, dob, rob); + +/* Return OK/warning status. */ + return j; + +/* Finished. */ + +} +/*---------------------------------------------------------------------- +** +** +** Copyright (C) 2013-2016, NumFOCUS Foundation. +** All rights reserved. +** +** This library is derived, with permission, from the International +** Astronomical Union's "Standards of Fundamental Astronomy" library, +** available from http://www.iausofa.org. +** +** The ERFA version is intended to retain identical functionality to +** the SOFA library, but made distinct through different function and +** file names, as set out in the SOFA license conditions. The SOFA +** original has a role as a reference standard for the IAU and IERS, +** and consequently redistribution is permitted only in its unaltered +** state. The ERFA version is not subject to this restriction and +** therefore can be included in distributions which do not support the +** concept of "read only" software. +** +** Although the intent is to replicate the SOFA API (other than +** replacement of prefix names) and results (with the exception of +** bugs; any that are discovered will be fixed), SOFA is not +** responsible for any errors found in this version of the library. +** +** If you wish to acknowledge the SOFA heritage, please acknowledge +** that you are using a library derived from SOFA, rather than SOFA +** itself. +** +** +** TERMS AND CONDITIONS +** +** Redistribution and use in source and binary forms, with or without +** modification, are permitted provided that the following conditions +** are met: +** +** 1 Redistributions of source code must retain the above copyright +** notice, this list of conditions and the following disclaimer. +** +** 2 Redistributions in binary form must reproduce the above copyright +** notice, this list of conditions and the following disclaimer in +** the documentation and/or other materials provided with the +** distribution. +** +** 3 Neither the name of the Standards Of Fundamental Astronomy Board, +** the International Astronomical Union nor the names of its +** contributors may be used to endorse or promote products derived +** from this software without specific prior written permission. +** +** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS +** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT +** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS +** FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE +** COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, +** INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, +** BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; +** LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER +** CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT +** LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN +** ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE +** POSSIBILITY OF SUCH DAMAGE. +** +*/ |