#include "sofa.h" int iauApio13(double utc1, double utc2, double dut1, double elong, double phi, double hm, double xp, double yp, double phpa, double tc, double rh, double wl, iauASTROM *astrom) /* ** - - - - - - - - - - ** i a u 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. ** ** This function is part of the International Astronomical Union's ** SOFA (Standards of Fundamental Astronomy) software collection. ** ** Status: support function. ** ** 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 iauASTROM* 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 iauDtf2d 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 iauDat 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 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 ** iauApc 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 ** ** iauApcg iauApcg13 geocentric ICRS <-> GCRS ** iauApci iauApci13 terrestrial ICRS <-> CIRS ** iauApco iauApco13 terrestrial ICRS <-> observed ** iauApcs iauApcs13 space ICRS <-> GCRS ** iauAper iauAper13 terrestrial update Earth rotation ** iauApio iauApio13 terrestrial CIRS <-> observed ** ** Those with names ending in "13" use contemporary SOFA 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 iauAtioq and iauAtoiq. ** ** Called: ** iauUtctai UTC to TAI ** iauTaitt TAI to TT ** iauUtcut1 UTC to UT1 ** iauSp00 the TIO locator s', IERS 2000 ** iauEra00 Earth rotation angle, IAU 2000 ** iauRefco refraction constants for given ambient conditions ** iauApio astrometry parameters, CIRS-observed ** ** This revision: 2013 October 9 ** ** SOFA release 2016-05-03 ** ** Copyright (C) 2016 IAU SOFA Board. See notes at end. */ { int j; double tai1, tai2, tt1, tt2, ut11, ut12, sp, theta, refa, refb; /* UTC to other time scales. */ j = iauUtctai(utc1, utc2, &tai1, &tai2); if ( j < 0 ) return -1; j = iauTaitt(tai1, tai2, &tt1, &tt2); j = iauUtcut1(utc1, utc2, dut1, &ut11, &ut12); if ( j < 0 ) return -1; /* TIO locator s'. */ sp = iauSp00(tt1, tt2); /* Earth rotation angle. */ theta = iauEra00(ut11, ut12); /* Refraction constants A and B. */ iauRefco(phpa, tc, rh, wl, &refa, &refb); /* CIRS <-> observed astrometry parameters. */ iauApio(sp, theta, elong, phi, hm, xp, yp, refa, refb, astrom); /* Return any warning status. */ return j; /* Finished. */ /*---------------------------------------------------------------------- ** ** Copyright (C) 2016 ** Standards Of Fundamental Astronomy Board ** of the International Astronomical Union. ** ** ===================== ** SOFA Software License ** ===================== ** ** NOTICE TO USER: ** ** BY USING THIS SOFTWARE YOU ACCEPT THE FOLLOWING SIX TERMS AND ** CONDITIONS WHICH APPLY TO ITS USE. ** ** 1. The Software is owned by the IAU SOFA Board ("SOFA"). ** ** 2. Permission is granted to anyone to use the SOFA software for any ** purpose, including commercial applications, free of charge and ** without payment of royalties, subject to the conditions and ** restrictions listed below. ** ** 3. You (the user) may copy and distribute SOFA source code to others, ** and use and adapt its code and algorithms in your own software, ** on a world-wide, royalty-free basis. That portion of your ** distribution that does not consist of intact and unchanged copies ** of SOFA source code files is a "derived work" that must comply ** with the following requirements: ** ** a) Your work shall be marked or carry a statement that it ** (i) uses routines and computations derived by you from ** software provided by SOFA under license to you; and ** (ii) does not itself constitute software provided by and/or ** endorsed by SOFA. ** ** b) The source code of your derived work must contain descriptions ** of how the derived work is based upon, contains and/or differs ** from the original SOFA software. ** ** c) The names of all routines in your derived work shall not ** include the prefix "iau" or "sofa" or trivial modifications ** thereof such as changes of case. ** ** d) The origin of the SOFA components of your derived work must ** not be misrepresented; you must not claim that you wrote the ** original software, nor file a patent application for SOFA ** software or algorithms embedded in the SOFA software. ** ** e) These requirements must be reproduced intact in any source ** distribution and shall apply to anyone to whom you have ** granted a further right to modify the source code of your ** derived work. ** ** Note that, as originally distributed, the SOFA software is ** intended to be a definitive implementation of the IAU standards, ** and consequently third-party modifications are discouraged. All ** variations, no matter how minor, must be explicitly marked as ** such, as explained above. ** ** 4. You shall not cause the SOFA software to be brought into ** disrepute, either by misuse, or use for inappropriate tasks, or ** by inappropriate modification. ** ** 5. The SOFA software is provided "as is" and SOFA makes no warranty ** as to its use or performance. SOFA does not and cannot warrant ** the performance or results which the user may obtain by using the ** SOFA software. SOFA makes no warranties, express or implied, as ** to non-infringement of third party rights, merchantability, or ** fitness for any particular purpose. In no event will SOFA be ** liable to the user for any consequential, incidental, or special ** damages, including any lost profits or lost savings, even if a ** SOFA representative has been advised of such damages, or for any ** claim by any third party. ** ** 6. The provision of any version of the SOFA software under the terms ** and conditions specified herein does not imply that future ** versions will also be made available under the same terms and ** conditions. * ** In any published work or commercial product which uses the SOFA ** software directly, acknowledgement (see www.iausofa.org) is ** appreciated. ** ** Correspondence concerning SOFA software should be addressed as ** follows: ** ** By email: sofa@ukho.gov.uk ** By post: IAU SOFA Center ** HM Nautical Almanac Office ** UK Hydrographic Office ** Admiralty Way, Taunton ** Somerset, TA1 2DN ** United Kingdom ** **--------------------------------------------------------------------*/ }