SUBROUTINE iau_NUT06A ( DATE1, DATE2, DPSI, DEPS ) *+ * - - - - - - - - - - - * i a u _ N U T 0 6 A * - - - - - - - - - - - * * IAU 2000A nutation with adjustments to match the IAU 2006 precession. * * Given: * DATE1,DATE2 d TT as a 2-part Julian Date (Note 1) * * Returned: * DPSI,DEPS d nutation, luni-solar + planetary (Note 2) * * Status: canonical model. * * 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 nutation components in longitude and obliquity are in radians * and with respect to the mean equinox and ecliptic of date, * IAU 2006 precession model (Hilton et al. 2006, Capitaine et al. * 2005). * * 3) The routine first computes the IAU 2000A nutation, then applies * adjustments for (i) the consequences of the change in obliquity * from the IAU 1980 ecliptic to the IAU 2006 ecliptic and (ii) the * secular variation in the Earth's dynamical flattening. * * 4) The present routine provides classical nutation, complementing * the IAU 2000 frame bias and IAU 2006 precession. It delivers a * pole which is at current epochs accurate to a few tens of * microarcseconds, apart from the free core nutation. * * Called: * iau_NUT00A nutation, IAU 2000A * * Reference: * * Wallace, P.T. & Capitaine, N., 2006, Astron.Astrophys. 459, 981 * * This revision: 2007 February 27 * * Copyright (C) 2007 IAU SOFA Review Board. See notes at end. * *----------------------------------------------------------------------- IMPLICIT NONE DOUBLE PRECISION DATE1, DATE2, DPSI, DEPS * Reference epoch (J2000), JD DOUBLE PRECISION DJ0 PARAMETER ( DJ0 = 2451545D0 ) * Days per Julian century DOUBLE PRECISION DJC PARAMETER ( DJC = 36525D0 ) * Miscellaneous DOUBLE PRECISION T, FJ2, DP, DE * - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - * Interval between fundamental date J2000.0 and given date (JC). T = ( ( DATE1-DJ0 ) + DATE2 ) / DJC * Factor correcting for secular variation of J2. FJ2 = -2.7774D-6 * T * Obtain IAU 2000A nutation. CALL iau_NUT00A ( DATE1, DATE2, DP, DE ) * Apply P03 adjustments (Wallace & Capitaine, 2006, Eqs.5). DPSI = DP + DP * ( 0.4697D-6 + FJ2 ) DEPS = DE + DE * FJ2 * Finished. *+---------------------------------------------------------------------- * * Copyright (C) 2007 * 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. 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