SUBROUTINE iau_UTCTAI ( UTC1, UTC2, TAI1, TAI2, J ) *+ * - - - - - - - - - - - * i a u _ U T C T A I * - - - - - - - - - - - * * Time scale transformation: Coordinated Universal Time, UTC, to * International Atomic Time, TAI. * * This routine is part of the International Astronomical Union's * SOFA (Standards of Fundamental Astronomy) software collection. * * Status: canonical. * * Given: * UTC1,UTC2 d UTC as a 2-part quasi Julian Date (Notes 1-4) * * Returned: * TAI1,TAI2 d TAI as a 2-part Julian Date (Note 5) * J i 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 routine * is that the JD day represents UTC days whether the length is * 86399, 86400 or 86401 SI seconds. In the 1960-1972 era there were * smaller jumps (in either direction) each time the linear UTC(TAI) * expression was changed, and these "mini-leaps" are also included * in the SOFA convention. * * 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 iau_DAT for further details. * * 4) The routine iau_DTF2D 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) The returned TAI1,TAI2 are such that their sum is the TAI Julian * Date. * * Called: * iau_JD2CAL JD to Gregorian calendar * iau_DAT delta(AT) = TAI-UTC * iau_CAL2JD Gregorian calendar to JD * * 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) * * This revision: 2019 June 20 * * SOFA release 2021-05-12 * * Copyright (C) 2021 IAU SOFA Board. See notes at end. * *----------------------------------------------------------------------- IMPLICIT NONE DOUBLE PRECISION UTC1, UTC2, TAI1, TAI2 INTEGER J * Days to seconds DOUBLE PRECISION D2S PARAMETER ( D2S = 86400D0 ) LOGICAL BIG1 INTEGER IY, IM, ID, JS, IYT, IMT, IDT DOUBLE PRECISION U1, U2, FD, DAT0, DAT12, W, DAT24, DLOD, DLEAP, : Z1, Z2, A2 * - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - * Put the two parts of the UTC into big-first order. BIG1 = ABS(UTC1) .GE. ABS(UTC2) IF ( BIG1 ) THEN U1 = UTC1 U2 = UTC2 ELSE U1 = UTC2 U2 = UTC1 END IF * Get TAI-UTC at 0h today. CALL iau_JD2CAL ( U1, U2, IY, IM, ID, FD, JS ) IF ( JS.NE.0 ) GO TO 9 CALL iau_DAT ( IY, IM, ID, 0D0, DAT0, JS ) IF ( JS.LT.0 ) GO TO 9 * Get TAI-UTC at 12h today (to detect drift). CALL iau_DAT ( IY, IM, ID, 0.5D0, DAT12, JS ) IF ( JS.LT.0 ) GO TO 9 * Get TAI-UTC at 0h tomorrow (to detect jumps). CALL iau_JD2CAL ( U1+1.5D0, U2-FD, IYT, IMT, IDT, W, JS ) IF ( JS.NE.0 ) GO TO 9 CALL iau_DAT ( IYT, IMT, IDT, 0D0, DAT24, JS ) IF ( JS.LT.0 ) GO TO 9 * Separate TAI-UTC change into per-day (DLOD) and any jump (DLEAP). DLOD = 2D0 * ( DAT12 - DAT0 ) DLEAP = DAT24 - ( DAT0 + DLOD ) * Remove any scaling applied to spread leap into preceding day. FD = FD * (D2S+DLEAP)/D2S * Scale from (pre-1972) UTC seconds to SI seconds. FD = FD * (D2S+DLOD)/D2S * Today's calendar date to 2-part JD. CALL iau_CAL2JD ( IY, IM, ID, Z1, Z2, JS ) IF ( JS.NE.0 ) GO TO 9 * Assemble the TAI result, preserving the UTC split and order. A2 = Z1 - U1 A2 = ( A2 + Z2 ) + ( FD + DAT0/D2S ) IF ( BIG1 ) THEN TAI1 = U1 TAI2 = A2 ELSE TAI1 = A2 TAI2 = U1 END IF * Status. 9 CONTINUE J = JS * Finished. *+---------------------------------------------------------------------- * * 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 * *----------------------------------------------------------------------- END