SUBROUTINE iau_DAT ( IY, IM, ID, FD, DELTAT, J ) *+ * - - - - - - - - * i a u _ D A T * - - - - - - - - * * For a given UTC date, calculate delta(AT) = TAI-UTC. * * :------------------------------------------: * : : * : IMPORTANT : * : : * : A new version of this routine must be : * : produced whenever a new leap second is : * : announced. There are five items to : * : change on each such occasion: : * : : * : 1) The parameter NDAT must be : * : increased by 1. : * : : * : 2) A new line must be added to the set : * : of DATA statements that initialize : * : the arrays IDATE and DATS. : * : : * : 3) The parameter IYV must be set to : * : the current year. : * : : * : 4) The "Latest leap second" comment : * : below must be set to the new leap : * : second date. : * : : * : 5) The "This revision" comment, later, : * : must be set to the current date. : * : : * : Change (3) must also be carried out : * : whenever the routine is re-issued, : * : even if no leap seconds have been : * : added. : * : : * : Latest leap second: 2008 December 31 : * : : * :__________________________________________: * * This routine is part of the International Astronomical Union's * SOFA (Standards of Fundamental Astronomy) software collection. * * Status: support routine. * * Given: * IY i UTC: year (Notes 1 and 2) * IM i month (Note 2) * ID i day (Notes 2 and 3) * FD d fraction of day (Note 4) * * Returned: * DELTAT d TAI minus UTC, seconds * J i status (Note 5): * 1 = dubious year (Note 1) * 0 = OK * -1 = bad year * -2 = bad month * -3 = bad day (Note 3) * -4 = bad fraction (Note 4) * * Notes: * * 1) UTC began at 1960 January 1.0 (JD 2436934.5) and it is improper * to call the routine with an earlier date. If this is attempted, * zero is returned together with a warning status. * * Because leap seconds cannot, in principle, be predicted in * advance, a reliable check for dates beyond the valid range is * impossible. To guard against gross errors, a year five or more * after the release year of the present routine (see parameter IYV) * is considered dubious. In this case a warning status is returned * but the result is computed in the normal way. * * For both too-early and too-late years, the warning status is J=+1. * This is distinct from the error status J=-1, which signifies a * year so early that JD could not be computed. * * 2) If the specified date is for a day which ends with a leap second, * the UTC-TAI value returned is for the period leading up to the * leap second. If the date is for a day which begins as a leap * second ends, the UTC-TAI returned is for the period following the * leap second. * * 3) The day number must be in the normal calendar range, for example * 1 through 30 for April. The "almanac" convention of allowing * such dates as January 0 and December 32 is not supported in this * routine, in order to avoid confusion near leap seconds. * * 4) The fraction of day is used only for dates before the introduction * of leap seconds, the first of which occurred at the end of 1971. * It is tested for validity (zero to less than 1 is the valid range) * even if not used; if invalid, zero is used and status J=-4 is * returned. For many applications, setting FD to zero is * acceptable; the resulting error is always less than 3 ms (and * occurs only pre-1972). * * 5) The status value returned in the case where there are multiple * errors refers to the first error detected. For example, if the * month and day are 13 and 32 respectively, J=-2 (bad month) will be * returned. * * 6) In cases where a valid result is not available, zero is returned. * * References: * * 1) For dates from 1961 January 1 onwards, the expressions from the * file ftp://maia.usno.navy.mil/ser7/tai-utc.dat are used. * * 2) The 5ms timestep at 1961 January 1 is taken from 2.58.1 (p87) of * the 1992 Explanatory Supplement. * * Called: * iau_CAL2JD Gregorian calendar to Julian Day number * * This revision: 2008 July 5 * * Copyright (C) 2008 IAU SOFA Review Board. See notes at end. * *----------------------------------------------------------------------- IMPLICIT NONE INTEGER IY, IM, ID DOUBLE PRECISION FD, DELTAT INTEGER J * Release year for this version of iau_DAT INTEGER IYV PARAMETER ( IYV = 2009 ) * Number of Delta(AT) changes (increase by 1 for each new leap second) INTEGER NDAT PARAMETER ( NDAT = 39 ) * Number of Delta(AT) expressions before leap seconds were introduced INTEGER NERA1 PARAMETER ( NERA1 = 14 ) * Dates (year, month) on which new Delta(AT) came into force INTEGER IDATE(2,NDAT) * New Delta(AT) which came into force on the given dates DOUBLE PRECISION DATS(NDAT) * Reference dates (MJD) and drift rates (s/day), pre leap seconds DOUBLE PRECISION DRIFT(2,NERA1) * Miscellaneous local variables LOGICAL MORE INTEGER JS, I, M, IS DOUBLE PRECISION DAT, DJM0, DJM * Dates and Delta(AT)s DATA (IDATE(I, 1),I=1,2),DATS(1) / 1960, 1, 1.4178180D0 / DATA (IDATE(I, 2),I=1,2),DATS(2) / 1961, 1, 1.4228180D0 / DATA (IDATE(I, 3),I=1,2),DATS(3) / 1961, 8, 1.3728180D0 / DATA (IDATE(I, 4),I=1,2),DATS(4) / 1962, 1, 1.8458580D0 / DATA (IDATE(I, 5),I=1,2),DATS(5) / 1963, 11, 1.9458580D0 / DATA (IDATE(I, 6),I=1,2),DATS(6) / 1964, 1, 3.2401300D0 / DATA (IDATE(I, 7),I=1,2),DATS(7) / 1964, 4, 3.3401300D0 / DATA (IDATE(I, 8),I=1,2),DATS(8) / 1964, 9, 3.4401300D0 / DATA (IDATE(I, 9),I=1,2),DATS(9) / 1965, 1, 3.5401300D0 / DATA (IDATE(I,10),I=1,2),DATS(10) / 1965, 3, 3.6401300D0 / DATA (IDATE(I,11),I=1,2),DATS(11) / 1965, 7, 3.7401300D0 / DATA (IDATE(I,12),I=1,2),DATS(12) / 1965, 9, 3.8401300D0 / DATA (IDATE(I,13),I=1,2),DATS(13) / 1966, 1, 4.3131700D0 / DATA (IDATE(I,14),I=1,2),DATS(14) / 1968, 2, 4.2131700D0 / DATA (IDATE(I,15),I=1,2),DATS(15) / 1972, 1, 10D0 / DATA (IDATE(I,16),I=1,2),DATS(16) / 1972, 7, 11D0 / DATA (IDATE(I,17),I=1,2),DATS(17) / 1973, 1, 12D0 / DATA (IDATE(I,18),I=1,2),DATS(18) / 1974, 1, 13D0 / DATA (IDATE(I,19),I=1,2),DATS(19) / 1975, 1, 14D0 / DATA (IDATE(I,20),I=1,2),DATS(20) / 1976, 1, 15D0 / DATA (IDATE(I,21),I=1,2),DATS(21) / 1977, 1, 16D0 / DATA (IDATE(I,22),I=1,2),DATS(22) / 1978, 1, 17D0 / DATA (IDATE(I,23),I=1,2),DATS(23) / 1979, 1, 18D0 / DATA (IDATE(I,24),I=1,2),DATS(24) / 1980, 1, 19D0 / DATA (IDATE(I,25),I=1,2),DATS(25) / 1981, 7, 20D0 / DATA (IDATE(I,26),I=1,2),DATS(26) / 1982, 7, 21D0 / DATA (IDATE(I,27),I=1,2),DATS(27) / 1983, 7, 22D0 / DATA (IDATE(I,28),I=1,2),DATS(28) / 1985, 7, 23D0 / DATA (IDATE(I,29),I=1,2),DATS(29) / 1988, 1, 24D0 / DATA (IDATE(I,30),I=1,2),DATS(30) / 1990, 1, 25D0 / DATA (IDATE(I,31),I=1,2),DATS(31) / 1991, 1, 26D0 / DATA (IDATE(I,32),I=1,2),DATS(32) / 1992, 7, 27D0 / DATA (IDATE(I,33),I=1,2),DATS(33) / 1993, 7, 28D0 / DATA (IDATE(I,34),I=1,2),DATS(34) / 1994, 7, 29D0 / DATA (IDATE(I,35),I=1,2),DATS(35) / 1996, 1, 30D0 / DATA (IDATE(I,36),I=1,2),DATS(36) / 1997, 7, 31D0 / DATA (IDATE(I,37),I=1,2),DATS(37) / 1999, 1, 32D0 / DATA (IDATE(I,38),I=1,2),DATS(38) / 2006, 1, 33D0 / DATA (IDATE(I,39),I=1,2),DATS(39) / 2009, 1, 34D0 / * Reference dates and drift rates DATA (DRIFT(I, 1),I=1,2) / 37300D0, 0.001296D0 / DATA (DRIFT(I, 2),I=1,2) / 37300D0, 0.001296D0 / DATA (DRIFT(I, 3),I=1,2) / 37300D0, 0.001296D0 / DATA (DRIFT(I, 4),I=1,2) / 37665D0, 0.0011232D0 / DATA (DRIFT(I, 5),I=1,2) / 37665D0, 0.0011232D0 / DATA (DRIFT(I, 6),I=1,2) / 38761D0, 0.001296D0 / DATA (DRIFT(I, 7),I=1,2) / 38761D0, 0.001296D0 / DATA (DRIFT(I, 8),I=1,2) / 38761D0, 0.001296D0 / DATA (DRIFT(I, 9),I=1,2) / 38761D0, 0.001296D0 / DATA (DRIFT(I,10),I=1,2) / 38761D0, 0.001296D0 / DATA (DRIFT(I,11),I=1,2) / 38761D0, 0.001296D0 / DATA (DRIFT(I,12),I=1,2) / 38761D0, 0.001296D0 / DATA (DRIFT(I,13),I=1,2) / 39126D0, 0.002592D0 / DATA (DRIFT(I,14),I=1,2) / 39126D0, 0.002592D0 / * - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - * Initialize the result to zero and the status to OK. DAT = 0D0 JS = 0 * If invalid fraction of a day, set error status and give up. IF ( FD.LT.0D0 .OR. FD.GE.1D0 ) THEN JS = -4 GO TO 9000 END IF * Convert the date into an MJD. CALL iau_CAL2JD ( IY, IM, ID, DJM0, DJM, JS ) * If invalid year, month, or day, give up. IF ( JS .LT. 0 ) GO TO 9000 * If pre-UTC year, set warning status and give up. IF ( IY .LT. IDATE(1,1) ) THEN JS = 1 GO TO 9000 END IF * If suspiciously late year, set warning status but proceed. IF ( IY .GT. IYV+5 ) JS = 1 * Combine year and month. M = 12*IY+IM * Prepare to search the tables. MORE = .TRUE. * Find the most recent table entry. DO 1 I=NDAT,1,-1 IF ( MORE ) THEN IS = I MORE = M .LT. ( 12*IDATE(1,I) + IDATE(2,I) ) END IF 1 CONTINUE * Get the Delta(AT). DAT = DATS(IS) * If pre-1972, adjust for drift. IF ( IS .LE. NERA1 ) DAT = DAT + : ( DJM + FD - DRIFT(1,IS) ) * DRIFT(2,IS) * Return the Delta(AT) value and the status. 9000 CONTINUE DELTAT = DAT J = JS * Finished. *+----------------------------------------------------------------------- * * Copyright (C) 2008 * Standards Of Fundamental Astronomy Review 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 Review Board ("the Board"). * * 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 adapt the SOFA software and its * algorithms for your own purposes and you may copy and distribute * a resulting "derived work" to others on a world-wide, royalty-free * basis, provided that the derived work complies 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 contain * software provided by SOFA or software that has been distributed * by or endorsed by SOFA. * * b) The source code of your derived work must contain descriptions * of how the derived work is based upon and/or differs from the * original SOFA software. * * c) The name(s) of all routine(s) that you distribute shall differ * from the SOFA names, even when the SOFA content has not been * otherwise changed. * * d) The routine-naming prefix "iau" shall not be used. * * e) 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. * * f) 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. * * 4. In any published work or commercial products which includes * results achieved by using the SOFA software, you shall acknowledge * that the SOFA software was used in obtaining those results. * * 5. You shall not cause the SOFA software to be brought into * disrepute, either by misuse, or use for inappropriate tasks, or by * inappropriate modification. * * 6. The SOFA software is provided "as is" and the Board makes no * warranty as to its use or performance. The Board does not and * cannot warrant the performance or results which the user may obtain * by using the SOFA software. The Board 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 the Board be liable to the user for any consequential, * incidental, or special damages, including any lost profits or lost * savings, even if a Board representative has been advised of such * damages, or for any claim by any third party. * * 7. 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. * * Correspondence concerning SOFA software should be addressed as * follows: * * Internet email: sofa@rl.ac.uk * Postal address: IAU SOFA Center * Rutherford Appleton Laboratory * Chilton, Didcot, Oxon OX11 0QX * United Kingdom * *----------------------------------------------------------------------- END