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Diffstat (limited to 'ast/erfa/atci13.c')
| -rw-r--r-- | ast/erfa/atci13.c | 159 |
1 files changed, 159 insertions, 0 deletions
diff --git a/ast/erfa/atci13.c b/ast/erfa/atci13.c new file mode 100644 index 0000000..40a3a04 --- /dev/null +++ b/ast/erfa/atci13.c @@ -0,0 +1,159 @@ +#include "erfa.h" + +void eraAtci13(double rc, double dc, + double pr, double pd, double px, double rv, + double date1, double date2, + double *ri, double *di, double *eo) +/* +** - - - - - - - - - - +** e r a A t c i 1 3 +** - - - - - - - - - - +** +** Transform ICRS star data, epoch J2000.0, to CIRS. +** +** Given: +** rc double ICRS right ascension at J2000.0 (radians, Note 1) +** dc double ICRS declination at J2000.0 (radians, Note 1) +** pr double RA proper motion (radians/year; Note 2) +** pd double Dec proper motion (radians/year) +** px double parallax (arcsec) +** rv double radial velocity (km/s, +ve if receding) +** date1 double TDB as a 2-part... +** date2 double ...Julian Date (Note 3) +** +** Returned: +** ri,di double* CIRS geocentric RA,Dec (radians) +** eo double* equation of the origins (ERA-GST, Note 5) +** +** Notes: +** +** 1) Star data for an epoch other than J2000.0 (for example from the +** Hipparcos catalog, which has an epoch of J1991.25) will require a +** preliminary call to eraPmsafe before use. +** +** 2) The proper motion in RA is dRA/dt rather than cos(Dec)*dRA/dt. +** +** 3) The TDB date date1+date2 is a Julian Date, apportioned in any +** convenient way between the two arguments. For example, +** JD(TDB)=2450123.8g could be expressed in any of these ways, among +** others: +** +** date1 date2 +** +** 2450123.8g 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. For most +** applications of this function the choice will not be at all +** critical. +** +** TT can be used instead of TDB without any significant impact on +** accuracy. +** +** 4) The available accuracy is better than 1 milliarcsecond, limited +** mainly by the precession-nutation model that is used, namely +** IAU 2000A/2006. Very close to solar system bodies, additional +** errors of up to several milliarcseconds can occur because of +** unmodeled light deflection; however, the Sun's contribution is +** taken into account, to first order. The accuracy limitations of +** the ERFA function eraEpv00 (used to compute Earth position and +** velocity) can contribute aberration errors of up to +** 5 microarcseconds. Light deflection at the Sun's limb is +** uncertain at the 0.4 mas level. +** +** 5) Should the transformation to (equinox based) apparent place be +** required rather than (CIO based) intermediate place, subtract the +** equation of the origins from the returned right ascension: +** RA = RI - EO. (The eraAnp function can then be applied, as +** required, to keep the result in the conventional 0-2pi range.) +** +** Called: +** eraApci13 astrometry parameters, ICRS-CIRS, 2013 +** eraAtciq quick ICRS to CIRS +** +** Copyright (C) 2013-2016, NumFOCUS Foundation. +** Derived, with permission, from the SOFA library. See notes at end of file. +*/ +{ +/* Star-independent astrometry parameters */ + eraASTROM astrom; + + +/* The transformation parameters. */ + eraApci13(date1, date2, &astrom, eo); + +/* ICRS (epoch J2000.0) to CIRS. */ + eraAtciq(rc, dc, pr, pd, px, rv, &astrom, ri, di); + +/* Finished. */ + +} +/*---------------------------------------------------------------------- +** +** +** 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. +** +*/ |