SUBROUTINE iau_BP00 ( DATE1, DATE2, RB, RP, RBP ) *+ * - - - - - - - - - * i a u _ B P 0 0 * - - - - - - - - - * * Frame bias and precession, IAU 2000. * * This routine is part of the International Astronomical Union's * SOFA (Standards of Fundamental Astronomy) software collection. * * Status: canonical model. * * Given: * DATE1,DATE2 d TT as a 2-part Julian Date (Note 1) * * Returned: * RB d(3,3) frame bias matrix (Note 2) * RP d(3,3) precession matrix (Note 3) * RBP d(3,3) bias-precession matrix (Note 4) * * Notes: * * 1) The TT date DATE1+DATE2 is a Julian Date, apportioned in any * convenient way between the two arguments. For example, * JD(TT)=2450123.7 could be expressed in any of these ways, * among others: * * DATE1 DATE2 * * 2450123.7D0 0D0 (JD method) * 2451545D0 -1421.3D0 (J2000 method) * 2400000.5D0 50123.2D0 (MJD method) * 2450123.5D0 0.2D0 (date & time method) * * The JD method is the most natural and convenient to use in * cases where the loss of several decimal digits of resolution * is acceptable. The J2000 method is best matched to the way * the argument is handled internally and will deliver the * optimum resolution. The MJD method and the date & time methods * are both good compromises between resolution and convenience. * * 2) The matrix RB transforms vectors from GCRS to mean J2000 by * applying frame bias. * * 3) The matrix RP transforms vectors from J2000 mean equator and * equinox to mean equator and equinox of date by applying * precession. * * 4) The matrix RBP transforms vectors from GCRS to mean equator and * equinox of date by applying frame bias then precession. It is the * product RP x RB. * * Called: * iau_BI00 frame bias components, IAU 2000 * iau_PR00 IAU 2000 precession adjustments * iau_IR initialize r-matrix to identity * iau_RX rotate around X-axis * iau_RY rotate around Y-axis * iau_RZ rotate around Z-axis * iau_RXR product of two r-matrices * * Reference: * * Capitaine, N., Chapront, J., Lambert, S. and Wallace, P., * "Expressions for the Celestial Intermediate Pole and Celestial * Ephemeris Origin consistent with the IAU 2000A precession-nutation * model", Astronomy & Astrophysics, 400, 1145-1154 (2003) * * n.b. The celestial ephemeris origin (CEO) was renamed "celestial * intermediate origin" (CIO) by IAU 2006 Resolution 2. * * This revision: 2007 April 11 * * Copyright (C) 2008 IAU SOFA Review Board. See notes at end. * *----------------------------------------------------------------------- IMPLICIT NONE DOUBLE PRECISION DATE1, DATE2, RB(3,3), RP(3,3), RBP(3,3) * Arcseconds to radians DOUBLE PRECISION DAS2R PARAMETER ( DAS2R = 4.848136811095359935899141D-6 ) * Reference epoch (J2000), JD DOUBLE PRECISION DJ0 PARAMETER ( DJ0 = 2451545D0 ) * Days per Julian century DOUBLE PRECISION DJC PARAMETER ( DJC = 36525D0 ) * J2000 obliquity (Lieske et al. 1977) DOUBLE PRECISION EPS0 PARAMETER ( EPS0 = 84381.448D0 * DAS2R ) DOUBLE PRECISION T, DPSIBI, DEPSBI, DRA0, : PSIA77, OMA77, CHIA, DPSIPR, DEPSPR, PSIA, OMA * - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - * Interval between fundamental epoch J2000.0 and current date (JC). T = ( ( DATE1-DJ0 ) + DATE2 ) / DJC * Frame bias. CALL iau_BI00 ( DPSIBI, DEPSBI, DRA0 ) * Precession angles (Lieske et al. 1977) PSIA77 = ( 5038.7784D0 + : ( -1.07259D0 + : ( -0.001147D0 ) * T ) * T ) * T * DAS2R OMA77 = EPS0 + ( : ( 0.05127D0 + : ( -0.007726D0 ) * T ) * T ) * T * DAS2R CHIA = ( 10.5526D0 + : ( -2.38064D0 + : ( -0.001125D0 ) * T ) * T ) * T * DAS2R * Apply IAU 2000 precession corrections. CALL iau_PR00 ( DATE1, DATE2, DPSIPR, DEPSPR ) PSIA = PSIA77 + DPSIPR OMA = OMA77 + DEPSPR * Frame bias matrix: GCRS to J2000. CALL iau_IR ( RB ) CALL iau_RZ ( DRA0, RB ) CALL iau_RY ( DPSIBI*SIN(EPS0), RB ) CALL iau_RX ( -DEPSBI, RB ) * Precession matrix: J2000 to mean of date. CALL iau_IR ( RP ) CALL iau_RX ( EPS0, RP ) CALL iau_RZ ( -PSIA, RP ) CALL iau_RX ( -OMA, RP ) CALL iau_RZ ( CHIA, RP ) * Bias-precession matrix: GCRS to mean of date. CALL iau_RXR ( RP, RB, RBP ) * 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. 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