SUBROUTINE iau_BI00 ( DPSIBI, DEPSBI, DRA ) *+ * - - - - - - - - - * i a u _ B I 0 0 * - - - - - - - - - * * Frame bias components of IAU 2000 precession-nutation models (part of * MHB_2000 with additions). * * This routine is part of the International Astronomical Union's * SOFA (Standards of Fundamental Astronomy) software collection. * * Status: canonical model. * * Returned: * DPSIBI,DEPSBI d longitude and obliquity corrections * DRA d the ICRS RA of the J2000 mean equinox * * Notes * * 1) The frame bias corrections in longitude and obliquity (radians) * are required in order to correct for the offset between the GCRS * pole and the mean J2000 pole. They define, with respect to the * GCRS frame, a J2000 mean pole that is consistent with the rest of * the IAU 2000A precession-nutation model. * * 2) In addition to the displacement of the pole, the complete * description of the frame bias requires also an offset in right * ascension. This is not part of the IAU 2000A model, and is from * Chapront et al. (2002). It is returned in radians. * * 3) This is a supplemented implementation of one aspect of the IAU * 2000A nutation model, formally adopted by the IAU General Assembly * in 2000, namely MHB2000 (Mathews et al. 2002). * * References * * Chapront, J., Chapront-Touze, M. & Francou, G., Astron.Astrophys., * 387, 700, 2002. * * Mathews, P.M., Herring, T.A., Buffet, B.A., "Modeling of nutation * and precession New nutation series for nonrigid Earth and * insights into the Earth's interior", J.Geophys.Res., 107, B4, * 2002. The MHB_2000 code itself was obtained on 9th September 2002 * from ftp //maia.usno.navy.mil/conv2000/chapter5/IAU2000A. * * This revision: 2002 December 23 * * Copyright (C) 2003 IAU SOFA Review Board. See notes at end. * *----------------------------------------------------------------------- IMPLICIT NONE DOUBLE PRECISION DPSIBI, DEPSBI, DRA * Arcseconds to radians DOUBLE PRECISION DAS2R PARAMETER ( DAS2R = 4.848136811095359935899141D-6 ) * The frame bias corrections in longitude and obliquity DOUBLE PRECISION DPBIAS, DEBIAS PARAMETER ( DPBIAS = -0.041775D0 * DAS2R, : DEBIAS = -0.0068192D0 * DAS2R ) * The ICRS RA of the J2000 equinox (Chapront et al., 2002) DOUBLE PRECISION DRA0 PARAMETER ( DRA0 = -0.0146D0 * DAS2R ) * - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - * Return the results (which are fixed). DPSIBI = DPBIAS DEPSBI = DEBIAS DRA = DRA0 * Finished. *+---------------------------------------------------------------------- * * Copyright (C) 2003 * 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