DOUBLE PRECISION FUNCTION iau_GST06A ( UTA, UTB, TTA, TTB ) *+ * - - - - - - - - - - - * i a u _ G S T 0 6 A * - - - - - - - - - - - * * Greenwich apparent sidereal time (consistent with IAU 2000 and 2006 * resolutions). * * This routine is part of the International Astronomical Union's * SOFA (Standards of Fundamental Astronomy) software collection. * * Status: canonical model. * * Given: * UTA, UTB d UT1 as a 2-part Julian Date (Notes 1,2) * TTA, TTB d TT as a 2-part Julian Date (Notes 1,2) * * Returned: * iau_GST06A d Greenwich apparent sidereal time (radians) * * Notes: * * 1) The UT1 and TT dates UTA+UTB and TTA+TTB respectively, are both * Julian Dates, apportioned in any convenient way between the * argument pairs. For example, JD=2450123.7 could be expressed in * any of these ways, among others: * * Part A Part B * * 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 (in the case of UT; the TT is not at all critical * in this respect). The J2000 and MJD methods are good compromises * between resolution and convenience. For UT, the date & time * method is best matched to the algorithm that is used by the Earth * rotation angle routine, called internally: maximum accuracy (or, * at least, minimum noise) is delivered when the UTA argument is for * 0hrs UT1 on the day in question and the UTB argument lies in the * range 0 to 1, or vice versa. * * 2) Both UT1 and TT are required, UT1 to predict the Earth rotation * and TT to predict the effects of precession-nutation. If UT1 is * used for both purposes, errors of order 100 microarcseconds * result. * * 3) This GAST is compatible with the IAU 2000/2006 resolutions and * must be used only in conjunction with IAU 2006 precession and * IAU 2000A nutation. * * 4) The result is returned in the range 0 to 2pi. * * Called: * iau_PNM06A classical NPB matrix, IAU 2006/2000A * iau_GST06 Greenwich apparent ST, IAU 2006, given NPB matrix * * Reference: * * Wallace, P.T. & Capitaine, N., 2006, Astron.Astrophys. 459, 981 * * This revision: 2008 May 12 * * SOFA release 2009-12-31 * * Copyright (C) 2009 IAU SOFA Review Board. See notes at end. * *----------------------------------------------------------------------- IMPLICIT NONE DOUBLE PRECISION UTA, UTB, TTA, TTB DOUBLE PRECISION RNPB(3,3) DOUBLE PRECISION iau_GST06 * - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - * Classical nutation x precession x bias matrix, IAU 2000A. CALL iau_PNM06A ( TTA, TTB, RNPB ) * Greenwich apparent sidereal time. iau_GST06A = iau_GST06 ( UTA, UTB, TTA, TTB, RNPB ) * 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