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. * * 3) The warning status "dubious year" flags UTCs that predate the * introduction of the time scale and 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: 2010 September 10 * * SOFA release 2010-12-01 * * Copyright (C) 2010 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, DATS, FDT, DATST, DDAT, Z1, Z2, A2 * - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - * Put the two parts of the UTC into big-first order. BIG1 = UTC1.GE.UTC2 IF ( BIG1 ) THEN U1 = UTC1 U2 = UTC2 ELSE U1 = UTC2 U2 = UTC1 END IF * Get TAI-UTC now. CALL iau_JD2CAL ( U1, U2, IY, IM, ID, FD, JS ) IF ( JS.NE.0 ) GO TO 9 CALL iau_DAT ( IY, IM, ID, FD, DATS, JS ) IF ( JS.LT.0 ) GO TO 9 * Get TAI-UTC tomorrow. CALL iau_JD2CAL ( U1+1.5D0, U2-FD, IYT, IMT, IDT, FDT, JS ) IF ( JS.NE.0 ) GO TO 9 CALL iau_DAT ( IYT, IMT, IDT, FDT, DATST, JS ) IF ( JS.LT.0 ) GO TO 9 * If today ends in a leap second, scale the fraction into SI days. DDAT = DATST - DATS IF ( ABS(DDAT).GT.0.5D0 ) FD = FD + FD*DDAT/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 + DATS/D2S ) IF ( BIG1 ) THEN TAI1 = U1 TAI2 = A2 ELSE TAI1 = A2 TAI2 = U1 END IF * Status. 9 CONTINUE IF ( JS.NE.0 ) JS = -1 J = JS * Finished. *+---------------------------------------------------------------------- * * Copyright (C) 2010 * Standards Of Fundamental Astronomy Board * of the International Astronomical Union. * * ===================== * SOFA Software License * ===================== * * NOTICE TO USER: * * BY USING THIS SOFTWARE YOU ACCEPT THE FOLLOWING 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. 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