SUBROUTINE iau_C2TEQX ( RBPN, GST, RPOM, RC2T ) *+ * - - - - - - - - - - - * i a u _ C 2 T E Q X * - - - - - - - - - - - * * Assemble the celestial to terrestrial matrix from equinox-based * components (the celestial-to-true matrix, the Greenwich Apparent * Sidereal Time and the polar motion matrix). * * This routine is part of the International Astronomical Union's * SOFA (Standards of Fundamental Astronomy) software collection. * * Status: support routine. * * Given: * RBPN d(3,3) celestial-to-true matrix * GST d Greenwich (apparent) Sidereal Time * RPOM d(3,3) polar-motion matrix * * Returned: * RC2T d(3,3) celestial-to-terrestrial matrix (Note 2) * * Notes: * * 1) This routine constructs the rotation matrix that transforms * vectors in the celestial system into vectors in the terrestrial * system. It does so starting from precomputed components, namely * the matrix which rotates from celestial coordinates to the * true equator and equinox of date, the Greenwich Apparent Sidereal * Time and the polar motion matrix. One use of the present routine * is when generating a series of celestial-to-terrestrial matrices * where only the Sidereal Time changes, avoiding the considerable * overhead of recomputing the precession-nutation more often than * necessary to achieve given accuracy objectives. * * 2) The relationship between the arguments is as follows: * * [TRS] = RPOM * R_3(GST) * RBPN * [CRS] * * = RC2T * [CRS] * * where [CRS] is a vector in the Geocentric Celestial Reference * System and [TRS] is a vector in the International Terrestrial * Reference System (see IERS Conventions 2003). * * Called: * iau_CR copy r-matrix * iau_RZ rotate around Z-axis * iau_RXR product of two r-matrices * * Reference: * * McCarthy, D. D., Petit, G. (eds.), IERS Conventions (2003), * IERS Technical Note No. 32, BKG (2004) * * This revision: 2006 November 13 * * SOFA release 2009-12-31 * * Copyright (C) 2009 IAU SOFA Review Board. See notes at end. * *----------------------------------------------------------------------- IMPLICIT NONE DOUBLE PRECISION RBPN(3,3), GST, RPOM(3,3), RC2T(3,3) DOUBLE PRECISION R(3,3) * - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - * Construct the matrix. CALL iau_CR ( RBPN, R ) CALL iau_RZ ( GST, R ) CALL iau_RXR ( RPOM, R, RC2T ) * Finished. *+---------------------------------------------------------------------- * * Copyright (C) 2009 * 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 ("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 name(s) of all routine(s) in your derived work shall not * include the prefix "iau_". * * 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. All * variations, no matter how minor, must be explicitly marked as * such, as explained above. * * 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 SOFA makes no warranty * as to its use or performance. SOFA does not and cannot warrant * the performance or results which the user may obtain by using the * SOFA software. SOFA 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 SOFA be * liable to the user for any consequential, incidental, or special * damages, including any lost profits or lost savings, even if a * SOFA 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: * * By email: sofa@rl.ac.uk * By post: IAU SOFA Center * STFC Rutherford Appleton Laboratory * Harwell Science and Innovation Campus * Didcot, Oxfordshire, OX11 0QX * United Kingdom * *---------------------------------------------------------------------- END