#include "erfa.h" int eraApio13(double utc1, double utc2, double dut1, double elong, double phi, double hm, double xp, double yp, double phpa, double tc, double rh, double wl, eraASTROM *astrom) /* ** - - - - - - - - - - ** e r a A p i o 1 3 ** - - - - - - - - - - ** ** For a terrestrial observer, prepare star-independent astrometry ** parameters for transformations between CIRS and observed ** coordinates. The caller supplies UTC, site coordinates, ambient air ** conditions and observing wavelength. ** ** Given: ** utc1 double UTC as a 2-part... ** utc2 double ...quasi Julian Date (Notes 1,2) ** dut1 double UT1-UTC (seconds) ** elong double longitude (radians, east +ve, Note 3) ** phi double geodetic latitude (radians, Note 3) ** 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: ** astrom eraASTROM* star-independent astrometry parameters: ** pmt double unchanged ** eb double[3] unchanged ** eh double[3] unchanged ** em double unchanged ** v double[3] unchanged ** bm1 double unchanged ** bpn double[3][3] unchanged ** along double longitude + s' (radians) ** xpl double polar motion xp wrt local meridian (radians) ** ypl double polar motion yp wrt local meridian (radians) ** sphi double sine of geodetic latitude ** cphi double cosine of geodetic latitude ** diurab double magnitude of diurnal aberration vector ** eral double "local" Earth rotation angle (radians) ** refa double refraction constant A (radians) ** refb double refraction constant B (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. ** ** Internally, the polar motion is stored in a form rotated onto ** the local meridian. ** ** 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) 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. ** ** 9) In cases where the caller wishes to supply his own Earth ** rotation information and refraction constants, the function ** eraApc can be used instead of the present function. ** ** 10) This is one of several functions that inserts into the astrom ** structure star-independent parameters needed for the chain of ** astrometric transformations ICRS <-> GCRS <-> CIRS <-> observed. ** ** The various functions support different classes of observer and ** portions of the transformation chain: ** ** functions observer transformation ** ** eraApcg eraApcg13 geocentric ICRS <-> GCRS ** eraApci eraApci13 terrestrial ICRS <-> CIRS ** eraApco eraApco13 terrestrial ICRS <-> observed ** eraApcs eraApcs13 space ICRS <-> GCRS ** eraAper eraAper13 terrestrial update Earth rotation ** eraApio eraApio13 terrestrial CIRS <-> observed ** ** Those with names ending in "13" use contemporary ERFA models to ** compute the various ephemerides. The others accept ephemerides ** supplied by the caller. ** ** The transformation from ICRS to GCRS covers space motion, ** parallax, light deflection, and aberration. From GCRS to CIRS ** comprises frame bias and precession-nutation. From CIRS to ** observed takes account of Earth rotation, polar motion, diurnal ** aberration and parallax (unless subsumed into the ICRS <-> GCRS ** transformation), and atmospheric refraction. ** ** 11) The context structure astrom produced by this function is used ** by eraAtioq and eraAtoiq. ** ** Called: ** eraUtctai UTC to TAI ** eraTaitt TAI to TT ** eraUtcut1 UTC to UT1 ** eraSp00 the TIO locator s', IERS 2000 ** eraEra00 Earth rotation angle, IAU 2000 ** eraRefco refraction constants for given ambient conditions ** eraApio astrometry parameters, CIRS-observed ** ** Copyright (C) 2013-2017, NumFOCUS Foundation. ** Derived, with permission, from the SOFA library. See notes at end of file. */ { int j; double tai1, tai2, tt1, tt2, ut11, ut12, sp, theta, refa, refb; /* UTC to other time scales. */ j = eraUtctai(utc1, utc2, &tai1, &tai2); if ( j < 0 ) return -1; j = eraTaitt(tai1, tai2, &tt1, &tt2); j = eraUtcut1(utc1, utc2, dut1, &ut11, &ut12); if ( j < 0 ) return -1; /* TIO locator s'. */ sp = eraSp00(tt1, tt2); /* Earth rotation angle. */ theta = eraEra00(ut11, ut12); /* Refraction constants A and B. */ eraRefco(phpa, tc, rh, wl, &refa, &refb); /* CIRS <-> observed astrometry parameters. */ eraApio(sp, theta, elong, phi, hm, xp, yp, refa, refb, astrom); /* Return any warning status. */ return j; /* Finished. */ } /*---------------------------------------------------------------------- ** ** ** Copyright (C) 2013-2017, 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. ** */