DOUBLE PRECISION FUNCTION iau_EPB ( DJ1, DJ2 ) *+ * - - - - - - - - * i a u _ E P B * - - - - - - - - * * Julian Date to Besselian Epoch. * * This routine is part of the International Astronomical Union's * SOFA (Standards of Fundamental Astronomy) software collection. * * Status: support routine. * * Given: * DJ1,DJ2 d Julian Date (see note) * * The result is the Besselian Epoch. * * Note: * * The Julian Date is supplied 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 DJ1 and * DJ2. The maximum resolution is achieved if DJ1 is 2451545D0 * (J2000). * * Reference: * * Lieske,J.H., 1979. Astron.Astrophys.,73,282. * * This revision: 2003 January 14 * * Copyright (C) 2003 IAU SOFA Review Board. See notes at end. * *----------------------------------------------------------------------- IMPLICIT NONE DOUBLE PRECISION DJ1, DJ2 * J2000 as a Julian Date DOUBLE PRECISION DJ0 PARAMETER ( DJ0 = 2451545D0 ) * J2000 minus B1900 (2415019.81352) in Julian days DOUBLE PRECISION D1900 PARAMETER ( D1900 = 36524.68648D0 ) * Length of tropical year B1900 (days) DOUBLE PRECISION TY PARAMETER ( TY = 365.242198781D0 ) * - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - iau_EPB = 1900D0 + ( ( DJ1-DJ0 ) + ( DJ2+D1900 ) ) / TY * Finished. *+---------------------------------------------------------------------- * * Copyright (C) 2003 * 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. The Software is made available free of charge for use by: * * a) private individuals for non-profit research; and * * b) non-profit educational, academic and research institutions. * * 3. Commercial use of the Software is specifically excluded from the * terms and conditions of this license. Commercial use of the * Software is subject to the prior written agreement of the Board on * terms to be agreed. * * 4. The provision of any version of the 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. * * 5. The user may modify the Software for his/her own purposes. The * user may distribute the modified software provided that the Board * is informed and that a copy of the modified software is made * available to the Board on request. All modifications made by the * user shall be clearly identified to show how the modified software * differs from the original Software, and the name(s) of the * affected routine(s) shall be changed. The original SOFA Software * License text must be present. * * 6. In any published work produced by the user and which includes * results achieved by using the Software, the user shall acknowledge * that the Software was used in producing the information contained * in such publication. * * 7. The user may incorporate or embed the Software into other software * products which he/she may then give away free of charge but not * sell provided the user makes due acknowledgement of the use which * he/she has made of the Software in creating such software * products. Any redistribution of the Software in this way shall be * made under the same terms and conditions under which the user * received it from the SOFA Center. * * 8. The user shall not cause the Software to be brought into * disrepute, either by misuse, or use for inappropriate tasks, or by * inappropriate modification. * * 9. The Software is provided to the user "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 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. * * 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