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/************************************************************************
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LUNAR SOLUTION ELP2000-82B
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by Chapront-Touze M., Chapront J.
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ftp://ftp.imcce.fr/pub/ephem/moon/elp82b
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I (Johannes Gajdosik) have just taken the Fortran code and data
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obtained from above and used it to create this piece of software.
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I can neigther allow nor forbid the usage of ELP2000-82B.
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The copyright notice below covers not the works of
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Chapront-Touze M. and Chapront J., but just my work,
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that is the compilation and rearrangement of
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the Fortran code and data obtained from above
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into the software supplied in this file.
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Copyright (c) 2005 Johannes Gajdosik
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Permission is hereby granted, free of charge, to any person obtaining a
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copy of this software and associated documentation files (the "Software"),
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to deal in the Software without restriction, including without limitation
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the rights to use, copy, modify, merge, publish, distribute, sublicense,
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and/or sell copies of the Software, and to permit persons to whom the
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Software is furnished to do so, subject to the following conditions:
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The above copyright notice and this permission notice shall be included
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in all copies or substantial portions of the Software.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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My implementation of ELP2000-82B has the following modifications compared to
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the original Fortran code:
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1) fundamentally rearrange the series into optimized instructions
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for fast calculation of the results
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2) units are: julian day, AU
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****************************************************************/
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void GetElp82bCoor(double jd,double xyz[3]);
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/* Return the rectangular coordinates of the earths moon
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on the given julian date jd expressed in dynamical time (TAI+32.184s).
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The origin of the xyz-coordinates is the center of the earth.
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The reference frame is "dynamical equinox and ecliptic J2000",
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which is the reference frame in VSOP87 and VSOP87A.
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According to vsop87.doc VSOP87 coordinates can be transformed to FK5 by
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X cos(psi) -sin(psi) 0 1 0 0 X
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Y = sin(psi) cos(psi) 0 * 0 cos(eps) -sin(eps) * Y
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Z FK5 0 0 1 0 sin(eps) cos(eps) Z VSOP87
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with psi = -0.0000275 degrees = -0.099 arcsec and
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eps = 23.4392803055556 degrees = 23d26m21.4091sec.
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http://ssd.jpl.nasa.gov/horizons_doc.html#frames says:
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"J2000" selects an Earth Mean-Equator and dynamical Equinox of
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Epoch J2000.0 inertial reference system, where the Epoch of J2000.0
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is the Julian date 2451545.0. "Mean" indicates nutation effects are
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ignored in the frame definition. The system is aligned with the
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IAU-sponsored J2000 frame of the Radio Source Catalog of the
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International Earth Rotational Service (ICRF).
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The ICRF is thought to differ from FK5 by at most 0.01 arcsec.
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From this I conclude that in the context of stellarium
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ICRF, J2000 and FK5 are the same, while the transformation
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ICRF <-> VSOP87 must be done with the matrix given above.
added
removed
src/stellplanet/elp82b.h
