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: 2008 May 24 * * 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 DJ00 PARAMETER ( DJ00 = 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-DJ00 ) + 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. 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