SUBROUTINE iau_CAL2JD ( IY, IM, ID, DJM0, DJM, J ) *+ * - - - - - - - - - - - * i a u _ C A L 2 J D * - - - - - - - - - - - * * Gregorian Calendar to Julian Date. * * This routine is part of the International Astronomical Union's * SOFA (Standards of Fundamental Astronomy) software collection. * * Status: support routine. * * Given: * IY,IM,ID i year, month, day in Gregorian calendar (Note 1) * * Returned: * DJM0 d MJD zero-point: always 2400000.5 * DJM d Modified Julian Date for 0 hrs * J i status: * 0 = OK * -1 = bad year (Note 3: JD not computed) * -2 = bad month (JD not computed) * -3 = bad day (JD computed) * * Notes: * * 1) The algorithm used is valid from -4800 March 1, but this * implementation rejects dates before -4799 January 1. * * 2) The Julian Date is returned in two pieces, in the usual SOFA * manner, which is designed to preserve time resolution. The * Julian Date is available as a single number by adding DJM0 and * DJM. * * 3) In early eras the conversion is from the "Proleptic Gregorian * Calendar"; no account is taken of the date(s) of adoption of * the Gregorian Calendar, nor is the AD/BC numbering convention * observed. * * Reference: * * Explanatory Supplement to the Astronomical Almanac, * P. Kenneth Seidelmann (ed), University Science Books (1992), * Section 12.92 (p604). * * This revision: 2001 September 16 * * Copyright (C) 2008 IAU SOFA Review Board. See notes at end. * *----------------------------------------------------------------------- IMPLICIT NONE INTEGER IY, IM, ID DOUBLE PRECISION DJM0, DJM INTEGER J, MY, IYPMY * Earliest year allowed (4800BC) INTEGER IYMIN PARAMETER ( IYMIN = -4799 ) * Month lengths in days INTEGER MTAB(12) DATA MTAB / 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 / * - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - * Preset status. J = 0 * Validate year. IF ( IY.LT.IYMIN ) THEN J = -1 ELSE * Validate month. IF ( IM.GE.1 .AND. IM.LE.12 ) THEN * Allow for leap year. IF ( MOD(IY,4) .EQ. 0 ) THEN MTAB(2) = 29 ELSE MTAB(2) = 28 END IF IF ( MOD(IY,100).EQ.0 .AND. MOD(IY,400).NE.0 ) MTAB(2) = 28 * Validate day. IF ( ID.LT.1 .OR. ID.GT.MTAB(IM) ) J = -3 * Result. MY = ( IM - 14 ) / 12 IYPMY = IY + MY DJM0 = 2400000.5D0 DJM = DBLE( ( 1461 * ( IYPMY + 4800 ) ) / 4 : + ( 367 * ( IM-2 - 12*MY ) ) / 12 : - ( 3 * ( ( IYPMY + 4900 ) / 100 ) ) / 4 : + ID - 2432076) * Bad month ELSE J = -2 END IF END IF * 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