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Diffstat (limited to 'ast/erfa/pvtob.c')
| -rw-r--r-- | ast/erfa/pvtob.c | 162 |
1 files changed, 162 insertions, 0 deletions
diff --git a/ast/erfa/pvtob.c b/ast/erfa/pvtob.c new file mode 100644 index 0000000..f808be7 --- /dev/null +++ b/ast/erfa/pvtob.c @@ -0,0 +1,162 @@ +#include "erfa.h" + +void eraPvtob(double elong, double phi, double hm, + double xp, double yp, double sp, double theta, + double pv[2][3]) +/* +** - - - - - - - - - +** e r a P v t o b +** - - - - - - - - - +** +** Position and velocity of a terrestrial observing station. +** +** Given: +** elong double longitude (radians, east +ve, Note 1) +** phi double latitude (geodetic, radians, Note 1) +** hm double height above ref. ellipsoid (geodetic, m) +** xp,yp double coordinates of the pole (radians, Note 2) +** sp double the TIO locator s' (radians, Note 2) +** theta double Earth rotation angle (radians, Note 3) +** +** Returned: +** pv double[2][3] position/velocity vector (m, m/s, CIRS) +** +** Notes: +** +** 1) The terrestrial coordinates are with respect to the ERFA_WGS84 +** reference ellipsoid. +** +** 2) xp and yp are the coordinates (in radians) of the Celestial +** Intermediate Pole with respect to the International Terrestrial +** Reference System (see IERS Conventions), measured along the +** meridians 0 and 90 deg west respectively. sp is the TIO locator +** s', in radians, which positions the Terrestrial Intermediate +** Origin on the equator. For many applications, xp, yp and +** (especially) sp can be set to zero. +** +** 3) If theta is Greenwich apparent sidereal time instead of Earth +** rotation angle, the result is with respect to the true equator +** and equinox of date, i.e. with the x-axis at the equinox rather +** than the celestial intermediate origin. +** +** 4) The velocity units are meters per UT1 second, not per SI second. +** This is unlikely to have any practical consequences in the modern +** era. +** +** 5) No validation is performed on the arguments. Error cases that +** could lead to arithmetic exceptions are trapped by the eraGd2gc +** function, and the result set to zeros. +** +** References: +** +** McCarthy, D. D., Petit, G. (eds.), IERS Conventions (2003), +** IERS Technical Note No. 32, BKG (2004) +** +** Urban, S. & Seidelmann, P. K. (eds), Explanatory Supplement to +** the Astronomical Almanac, 3rd ed., University Science Books +** (2013), Section 7.4.3.3. +** +** Called: +** eraGd2gc geodetic to geocentric transformation +** eraPom00 polar motion matrix +** eraTrxp product of transpose of r-matrix and p-vector +** +** Copyright (C) 2013-2014, NumFOCUS Foundation. +** Derived, with permission, from the SOFA library. See notes at end of file. +*/ +{ +/* Earth rotation rate in radians per UT1 second */ + const double OM = 1.00273781191135448 * ERFA_D2PI / ERFA_DAYSEC; + + double xyzm[3], rpm[3][3], xyz[3], x, y, z, s, c; + + +/* Geodetic to geocentric transformation (ERFA_WGS84). */ + (void) eraGd2gc(1, elong, phi, hm, xyzm); + +/* Polar motion and TIO position. */ + eraPom00(xp, yp, sp, rpm); + eraTrxp(rpm, xyzm, xyz); + x = xyz[0]; + y = xyz[1]; + z = xyz[2]; + +/* Functions of ERA. */ + s = sin(theta); + c = cos(theta); + +/* Position. */ + pv[0][0] = c*x - s*y; + pv[0][1] = s*x + c*y; + pv[0][2] = z; + +/* Velocity. */ + pv[1][0] = OM * ( -s*x - c*y ); + pv[1][1] = OM * ( c*x - s*y ); + pv[1][2] = 0.0; + +/* Finished. */ + +} +/*---------------------------------------------------------------------- +** +** +** Copyright (C) 2013-2014, 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. +** +*/ |