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Diffstat (limited to 'ast/erfa/bp00.c')
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diff --git a/ast/erfa/bp00.c b/ast/erfa/bp00.c new file mode 100644 index 0000000..dd387ea --- /dev/null +++ b/ast/erfa/bp00.c @@ -0,0 +1,181 @@ +#include "erfa.h" + +void eraBp00(double date1, double date2, + double rb[3][3], double rp[3][3], double rbp[3][3]) +/* +** - - - - - - - - +** e r a B p 0 0 +** - - - - - - - - +** +** Frame bias and precession, IAU 2000. +** +** Given: +** date1,date2 double TT as a 2-part Julian Date (Note 1) +** +** Returned: +** rb double[3][3] frame bias matrix (Note 2) +** rp double[3][3] precession matrix (Note 3) +** rbp double[3][3] bias-precession matrix (Note 4) +** +** 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 matrix rb transforms vectors from GCRS to mean J2000.0 by +** applying frame bias. +** +** 3) The matrix rp transforms vectors from J2000.0 mean equator and +** equinox to mean equator and equinox of date by applying +** precession. +** +** 4) The matrix rbp transforms vectors from GCRS to mean equator and +** equinox of date by applying frame bias then precession. It is +** the product rp x rb. +** +** 5) It is permissible to re-use the same array in the returned +** arguments. The arrays are filled in the order given. +** +** Called: +** eraBi00 frame bias components, IAU 2000 +** eraPr00 IAU 2000 precession adjustments +** eraIr initialize r-matrix to identity +** eraRx rotate around X-axis +** eraRy rotate around Y-axis +** eraRz rotate around Z-axis +** eraCr copy r-matrix +** eraRxr product of two r-matrices +** +** Reference: +** "Expressions for the Celestial Intermediate Pole and Celestial +** Ephemeris Origin consistent with the IAU 2000A precession- +** nutation model", Astron.Astrophys. 400, 1145-1154 (2003) +** +** n.b. The celestial ephemeris origin (CEO) was renamed "celestial +** intermediate origin" (CIO) by IAU 2006 Resolution 2. +** +** Copyright (C) 2013-2016, NumFOCUS Foundation. +** Derived, with permission, from the SOFA library. See notes at end of file. +*/ +{ +/* J2000.0 obliquity (Lieske et al. 1977) */ + const double EPS0 = 84381.448 * ERFA_DAS2R; + + double t, dpsibi, depsbi, dra0, psia77, oma77, chia, + dpsipr, depspr, psia, oma, rbw[3][3]; + + +/* Interval between fundamental epoch J2000.0 and current date (JC). */ + t = ((date1 - ERFA_DJ00) + date2) / ERFA_DJC; + +/* Frame bias. */ + eraBi00(&dpsibi, &depsbi, &dra0); + +/* Precession angles (Lieske et al. 1977) */ + psia77 = (5038.7784 + (-1.07259 + (-0.001147) * t) * t) * t * ERFA_DAS2R; + oma77 = EPS0 + ((0.05127 + (-0.007726) * t) * t) * t * ERFA_DAS2R; + chia = ( 10.5526 + (-2.38064 + (-0.001125) * t) * t) * t * ERFA_DAS2R; + +/* Apply IAU 2000 precession corrections. */ + eraPr00(date1, date2, &dpsipr, &depspr); + psia = psia77 + dpsipr; + oma = oma77 + depspr; + +/* Frame bias matrix: GCRS to J2000.0. */ + eraIr(rbw); + eraRz(dra0, rbw); + eraRy(dpsibi*sin(EPS0), rbw); + eraRx(-depsbi, rbw); + eraCr(rbw, rb); + +/* Precession matrix: J2000.0 to mean of date. */ + eraIr(rp); + eraRx(EPS0, rp); + eraRz(-psia, rp); + eraRx(-oma, rp); + eraRz(chia, rp); + +/* Bias-precession matrix: GCRS to mean of date. */ + eraRxr(rp, rbw, rbp); + + 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. +** +*/ |