#include "erfa.h" void eraNut06a(double date1, double date2, double *dpsi, double *deps) /* ** - - - - - - - - - - ** e r a N u t 0 6 a ** - - - - - - - - - - ** ** IAU 2000A nutation with adjustments to match the IAU 2006 ** precession. ** ** Given: ** date1,date2 double TT as a 2-part Julian Date (Note 1) ** ** Returned: ** dpsi,deps double nutation, luni-solar + planetary (Note 2) ** ** 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 ** ** 2450123.7 0.0 (JD method) ** 2451545.0 -1421.3 (J2000 method) ** 2400000.5 50123.2 (MJD method) ** 2450123.5 0.2 (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 function 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 form factor J2. ** ** 4) The present function 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: ** eraNut00a nutation, IAU 2000A ** ** References: ** ** Chapront, J., Chapront-Touze, M. & Francou, G. 2002, ** Astron.Astrophys. 387, 700 ** ** Lieske, J.H., Lederle, T., Fricke, W. & Morando, B. 1977, ** Astron.Astrophys. 58, 1-16 ** ** Mathews, P.M., Herring, T.A., Buffet, B.A. 2002, J.Geophys.Res. ** 107, B4. The MHB_2000 code itself was obtained on 9th September ** 2002 from ftp//maia.usno.navy.mil/conv2000/chapter5/IAU2000A. ** ** Simon, J.-L., Bretagnon, P., Chapront, J., Chapront-Touze, M., ** Francou, G., Laskar, J. 1994, Astron.Astrophys. 282, 663-683 ** ** Souchay, J., Loysel, B., Kinoshita, H., Folgueira, M. 1999, ** Astron.Astrophys.Supp.Ser. 135, 111 ** ** Wallace, P.T., "Software for Implementing the IAU 2000 ** Resolutions", in IERS Workshop 5.1 (2002) ** ** Copyright (C) 2013-2016, NumFOCUS Foundation. ** Derived, with permission, from the SOFA library. See notes at end of file. */ { double t, fj2, dp, de; /* Interval between fundamental date J2000.0 and given date (JC). */ t = ((date1 - ERFA_DJ00) + date2) / ERFA_DJC; /* Factor correcting for secular variation of J2. */ fj2 = -2.7774e-6 * t; /* Obtain IAU 2000A nutation. */ eraNut00a(date1, date2, &dp, &de); /* Apply P03 adjustments (Wallace & Capitaine, 2006, Eqs.5). */ *dpsi = dp + dp * (0.4697e-6 + fj2); *deps = de + de * fj2; return; } /*---------------------------------------------------------------------- ** ** ** Copyright (C) 2013-2016, NumFOCUS Foundation. ** All rights reserved. ** ** This library is derived, with permission, from the International ** Astronomical Union's "Standards of Fundamental Astronomy" library, ** available from http://www.iausofa.org. ** ** The ERFA version is intended to retain identical functionality to ** the SOFA library, but made distinct through different function and ** file names, as set out in the SOFA license conditions. The SOFA ** original has a role as a reference standard for the IAU and IERS, ** and consequently redistribution is permitted only in its unaltered ** state. The ERFA version is not subject to this restriction and ** therefore can be included in distributions which do not support the ** concept of "read only" software. ** ** Although the intent is to replicate the SOFA API (other than ** replacement of prefix names) and results (with the exception of ** bugs; any that are discovered will be fixed), SOFA is not ** responsible for any errors found in this version of the library. ** ** If you wish to acknowledge the SOFA heritage, please acknowledge ** that you are using a library derived from SOFA, rather than SOFA ** itself. ** ** ** TERMS AND CONDITIONS ** ** Redistribution and use in source and binary forms, with or without ** modification, are permitted provided that the following conditions ** are met: ** ** 1 Redistributions of source code must retain the above copyright ** notice, this list of conditions and the following disclaimer. ** ** 2 Redistributions in binary form must reproduce the above copyright ** notice, this list of conditions and the following disclaimer in ** the documentation and/or other materials provided with the ** distribution. ** ** 3 Neither the name of the Standards Of Fundamental Astronomy Board, ** the International Astronomical Union nor the names of its ** contributors may be used to endorse or promote products derived ** from this software without specific prior written permission. ** ** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS ** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT ** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS ** FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE ** COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, ** INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, ** BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; ** LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER ** CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT ** LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ** ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE ** POSSIBILITY OF SUCH DAMAGE. ** */