#include "sofa.h" void iauAper13(double ut11, double ut12, iauASTROM *astrom) /* ** - - - - - - - - - - ** i a u A p e r 1 3 ** - - - - - - - - - - ** ** In the star-independent astrometry parameters, update only the ** Earth rotation angle. The caller provides UT1, (n.b. not UTC). ** ** This function is part of the International Astronomical Union's ** SOFA (Standards of Fundamental Astronomy) software collection. ** ** Status: support function. ** ** Given: ** ut11 double UT1 as a 2-part... ** ut12 double ...Julian Date (Note 1) ** astrom iauASTROM* star-independent astrometry parameters: ** pmt double not used ** eb double[3] not used ** eh double[3] not used ** em double not used ** v double[3] not used ** bm1 double not used ** bpn double[3][3] not used ** along double longitude + s' (radians) ** xpl double not used ** ypl double not used ** sphi double not used ** cphi double not used ** diurab double not used ** eral double not used ** refa double not used ** refb double not used ** ** 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 unchanged ** xpl double unchanged ** ypl double unchanged ** sphi double unchanged ** cphi double unchanged ** diurab double unchanged ** eral double "local" Earth rotation angle (radians) ** refa double unchanged ** refb double unchanged ** ** Notes: ** ** 1) The UT1 date (n.b. not UTC) ut11+ut12 is a Julian Date, ** apportioned in any convenient way between the arguments ut11 and ** ut12. For example, JD(UT1)=2450123.7 could be expressed in any ** of these ways, among others: ** ** ut11 ut12 ** ** 2450123.7 0.0 (JD method) ** 2451545.0 -1421.3 (J2000 method) ** 2400000.5 50123.2 (MJD method) ** 2450123.5 0.2 (date & time method) ** ** The JD method is the most natural and convenient to use in cases ** where the loss of several decimal digits of resolution is ** acceptable. The J2000 and MJD methods are good compromises ** between resolution and convenience. The date & time method is ** best matched to the algorithm used: maximum precision is ** delivered when the ut11 argument is for 0hrs UT1 on the day in ** question and the ut12 argument lies in the range 0 to 1, or vice ** versa. ** ** 2) If the caller wishes to provide the Earth rotation angle itself, ** the function iauAper can be used instead. One use of this ** technique is to substitute Greenwich apparent sidereal time and ** thereby to support equinox based transformations directly. ** ** 3) 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. ** ** Called: ** iauAper astrometry parameters: update ERA ** iauEra00 Earth rotation angle, IAU 2000 ** ** This revision: 2013 September 25 ** ** SOFA release 2018-01-30 ** ** Copyright (C) 2018 IAU SOFA Board. See notes at end. */ { iauAper(iauEra00(ut11,ut12), astrom); /* Finished. */ /*---------------------------------------------------------------------- ** ** Copyright (C) 2018 ** 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 ** **--------------------------------------------------------------------*/ }