#include "sofa.h" int iauUtcut1(double utc1, double utc2, double dut1, double *ut11, double *ut12) /* ** - - - - - - - - - - ** i a u U t c u t 1 ** - - - - - - - - - - ** ** Time scale transformation: Coordinated Universal Time, UTC, to ** Universal Time, UT1. ** ** This function is part of the International Astronomical Union's ** SOFA (Standards of Fundamental Astronomy) software collection. ** ** Status: canonical. ** ** Given: ** utc1,utc2 double UTC as a 2-part quasi Julian Date (Notes 1-4) ** dut1 double Delta UT1 = UT1-UTC in seconds (Note 5) ** ** Returned: ** ut11,ut12 double UT1 as a 2-part Julian Date (Note 6) ** ** Returned (function value): ** int status: +1 = dubious year (Note 3) ** 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. ** ** 2) 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. ** ** 3) 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. ** ** 4) The function iauDtf2d converts from calendar date and time of ** day into 2-part Julian Date, and in the case of UTC implements ** the leap-second-ambiguity convention described above. ** ** 5) Delta UT1 can be obtained from tabulations provided by the ** International Earth Rotation and Reference Systems Service. ** It is the caller's responsibility to supply a dut1 argument ** containing the UT1-UTC value that matches the given UTC. ** ** 6) The returned ut11,ut12 are such that their sum is the UT1 Julian ** Date. ** ** References: ** ** McCarthy, D. D., Petit, G. (eds.), IERS Conventions (2003), ** IERS Technical Note No. 32, BKG (2004) ** ** Explanatory Supplement to the Astronomical Almanac, ** P. Kenneth Seidelmann (ed), University Science Books (1992) ** ** Called: ** iauJd2cal JD to Gregorian calendar ** iauDat delta(AT) = TAI-UTC ** iauUtctai UTC to TAI ** iauTaiut1 TAI to UT1 ** ** This revision: 2013 August 12 ** ** SOFA release 2021-01-25 ** ** Copyright (C) 2021 IAU SOFA Board. See notes at end. */ { int iy, im, id, js, jw; double w, dat, dta, tai1, tai2; /* Look up TAI-UTC. */ if ( iauJd2cal(utc1, utc2, &iy, &im, &id, &w) ) return -1; js = iauDat ( iy, im, id, 0.0, &dat); if ( js < 0 ) return -1; /* Form UT1-TAI. */ dta = dut1 - dat; /* UTC to TAI to UT1. */ jw = iauUtctai(utc1, utc2, &tai1, &tai2); if ( jw < 0 ) { return -1; } else if ( jw > 0 ) { js = jw; } if ( iauTaiut1(tai1, tai2, dta, ut11, ut12) ) return -1; /* Status. */ return js; /*---------------------------------------------------------------------- ** ** Copyright (C) 2021 ** 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 ** **--------------------------------------------------------------------*/ }