#include "erfa.h" void eraAper(double theta, eraASTROM *astrom) /* ** - - - - - - - - ** e r a A p e r ** - - - - - - - - ** ** In the star-independent astrometry parameters, update only the ** Earth rotation angle, supplied by the caller explicitly. ** ** Given: ** theta double Earth rotation angle (radians, Note 2) ** astrom eraASTROM* star-independent astrometry parameters: ** pmt double not used ** eb double[3] not used ** eh double[3] not used ** em double not used ** v double[3] not used ** bm1 double not used ** bpn double[3][3] not used ** along double longitude + s' (radians) ** xpl double not used ** ypl double not used ** sphi double not used ** cphi double not used ** diurab double not used ** eral double not used ** refa double not used ** refb double not used ** ** Returned: ** astrom eraASTROM* star-independent astrometry parameters: ** pmt double unchanged ** eb double[3] unchanged ** eh double[3] unchanged ** em double unchanged ** v double[3] unchanged ** bm1 double unchanged ** bpn double[3][3] unchanged ** along double unchanged ** xpl double unchanged ** ypl double unchanged ** sphi double unchanged ** cphi double unchanged ** diurab double unchanged ** eral double "local" Earth rotation angle (radians) ** refa double unchanged ** refb double unchanged ** ** Notes: ** ** 1) This function exists to enable sidereal-tracking applications to ** avoid wasteful recomputation of the bulk of the astrometry ** parameters: only the Earth rotation is updated. ** ** 2) For targets expressed as equinox based positions, such as ** classical geocentric apparent (RA,Dec), the supplied theta can be ** Greenwich apparent sidereal time rather than Earth rotation ** angle. ** ** 3) The function eraAper13 can be used instead of the present ** function, and starts from UT1 rather than ERA itself. ** ** 4) This is one of several functions that inserts into the astrom ** structure star-independent parameters needed for the chain of ** astrometric transformations ICRS <-> GCRS <-> CIRS <-> observed. ** ** The various functions support different classes of observer and ** portions of the transformation chain: ** ** functions observer transformation ** ** eraApcg eraApcg13 geocentric ICRS <-> GCRS ** eraApci eraApci13 terrestrial ICRS <-> CIRS ** eraApco eraApco13 terrestrial ICRS <-> observed ** eraApcs eraApcs13 space ICRS <-> GCRS ** eraAper eraAper13 terrestrial update Earth rotation ** eraApio eraApio13 terrestrial CIRS <-> observed ** ** Those with names ending in "13" use contemporary ERFA models to ** compute the various ephemerides. The others accept ephemerides ** supplied by the caller. ** ** The transformation from ICRS to GCRS covers space motion, ** parallax, light deflection, and aberration. From GCRS to CIRS ** comprises frame bias and precession-nutation. From CIRS to ** observed takes account of Earth rotation, polar motion, diurnal ** aberration and parallax (unless subsumed into the ICRS <-> GCRS ** transformation), and atmospheric refraction. ** ** Copyright (C) 2013-2017, NumFOCUS Foundation. ** Derived, with permission, from the SOFA library. See notes at end of file. */ { astrom->eral = theta + astrom->along; /* Finished. */ } /*---------------------------------------------------------------------- ** ** ** Copyright (C) 2013-2017, 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. 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