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 J2000.0 by * applying frame bias. * * 3) The matrix RP transforms vectors from J2000.0 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 * iau_CR copy r-matrix * * 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", Astron.Astrophys. 400, 1145-1154 (2003) * * n.b. The celestial ephemeris origin (CEO) was renamed "celestial * intermediate origin" (CIO) by IAU 2006 Resolution 2. * * This revision: 2013 August 21 * * SOFA release 2019-07-22 * * Copyright (C) 2019 IAU SOFA 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 (J2000.0), JD DOUBLE PRECISION DJ00 PARAMETER ( DJ00 = 2451545D0 ) * Days per Julian century DOUBLE PRECISION DJC PARAMETER ( DJC = 36525D0 ) * J2000.0 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, RBW(3,3) * - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - * 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 J2000.0. CALL iau_IR ( RBW ) CALL iau_RZ ( DRA0, RBW ) CALL iau_RY ( DPSIBI*SIN(EPS0), RBW ) CALL iau_RX ( -DEPSBI, RBW ) CALL iau_CR ( RBW, RB ) * Precession matrix: J2000.0 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, RBW, RBP ) * Finished. *+---------------------------------------------------------------------- * * Copyright (C) 2019 * Standards Of Fundamental Astronomy Board * of the International Astronomical Union. * * ===================== * SOFA Software License * ===================== * * NOTICE TO USER: * * BY USING THIS SOFTWARE YOU ACCEPT THE FOLLOWING SIX TERMS AND * CONDITIONS WHICH APPLY TO ITS USE. * * 1. The Software is owned by the IAU SOFA Board ("SOFA"). * * 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 distribute SOFA source code to others, * and use and adapt its code and algorithms in your own software, * on a world-wide, royalty-free basis. That portion of your * distribution that does not consist of intact and unchanged copies * of SOFA source code files is a "derived work" that must comply * 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 itself constitute software provided by and/or * endorsed by SOFA. * * b) The source code of your derived work must contain descriptions * of how the derived work is based upon, contains and/or differs * from the original SOFA software. * * c) The names of all routines in your derived work shall not * include the prefix "iau" or "sofa" or trivial modifications * thereof such as changes of case. * * d) 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. * * e) 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. * * Note that, as originally distributed, the SOFA software is * intended to be a definitive implementation of the IAU standards, * and consequently third-party modifications are discouraged. 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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. * * In any published work or commercial product which uses the SOFA * software directly, acknowledgement (see www.iausofa.org) is * appreciated. * * Correspondence concerning SOFA software should be addressed as * follows: * * By email: sofa@ukho.gov.uk * By post: IAU SOFA Center * HM Nautical Almanac Office * UK Hydrographic Office * Admiralty Way, Taunton * Somerset, TA1 2DN * United Kingdom * *----------------------------------------------------------------------- END