SUBROUTINE iau_TTTCG ( TT1, TT2, TCG1, TCG2, J ) *+ * - - - - - - - - - - * i a u _ T T T C G * - - - - - - - - - - * * Time scale transformation: Terrestrial Time, TT, to Geocentric * Coordinate Time, TCG. * * This routine is part of the International Astronomical Union's * SOFA (Standards of Fundamental Astronomy) software collection. * * Status: canonical. * * Given: * TT1,TT2 d TT as a 2-part Julian Date * * Returned: * TCG1,TCG2 d TCG as a 2-part Julian Date * J i status: 0 = OK * * Note: * * TT1+TT2 is Julian Date, apportioned in any convenient way between * the two arguments, for example where TT1 is the Julian Day Number * and TT2 is the fraction of a day. The returned TCG1,TCG2 follow * suit. * * References: * * McCarthy, D. D., Petit, G. (eds.), IERS Conventions (2003), * IERS Technical Note No. 32, BKG (2004) * * IAU 2000 Resolution B1.9 * * This revision: 2010 May 9 * * SOFA release 2012-03-01 * * Copyright (C) 2012 IAU SOFA Board. See notes at end. * *----------------------------------------------------------------------- IMPLICIT NONE DOUBLE PRECISION TT1, TT2, TCG1, TCG2 INTEGER J * JD for MJD 0 DOUBLE PRECISION DJM0 PARAMETER (DJM0 = 2400000.5D0 ) * 1977 Jan 1 00:00:32.184 TT, as MJD DOUBLE PRECISION T77T PARAMETER ( T77T = 43144.0003725D0 ) * L_G = 1 - dTT/dTCG DOUBLE PRECISION ELG PARAMETER ( ELG = 6.969290134D-10 ) * TT to TCG rate DOUBLE PRECISION ELGG PARAMETER ( ELGG = ELG/(1D0-ELG) ) * - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - * Result, safeguarding precision. IF ( TT1.GT.TT2 ) THEN TCG1 = TT1 TCG2 = TT2 + ( ( TT1-DJM0 ) + ( TT2-T77T ) ) * ELGG ELSE TCG1 = TT1 + ( ( TT2-DJM0 ) + ( TT1-T77T ) ) * ELGG TCG2 = TT2 END IF * Status (always OK). J = 0 * Finished. *+---------------------------------------------------------------------- * * Copyright (C) 2012 * 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 * *----------------------------------------------------------------------- END