SUBROUTINE iau_ATCI13 ( RC, DC, PR, PD, PX, RV, DATE1, DATE2, : RI, DI, EO ) *+ * - - - - - - - - - - - * i a u _ A T C I 1 3 * - - - - - - - - - - - * * Transform ICRS star data, epoch J2000.0, to CIRS. * * This routine is part of the International Astronomical Union's * SOFA (Standards of Fundamental Astronomy) software collection. * * Status: support routine. * * Given: * RC d ICRS right ascension at J2000.0 (radians, Note 1) * DC d ICRS declination at J2000.0 (radians, Note 1) * PR d RA proper motion (radians/year, Note 2) * PD d Dec proper motion (radians/year) * PX d parallax (arcsec) * RV d radial velocity (km/s, +ve if receding) * DATE1 d TDB as a 2-part... * DATE2 d ...Julian Date (Note 3) * * Returned: * RI,DI d CIRS geocentric RA,Dec (radians) * EO d equation of the origins (ERA-GST, radians, 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 iau_PMSAFE 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)=2450123.7 could be expressed in any of these ways, among * others: * * DATE1 DATE2 * * 2450123.7D0 0D0 (JD method) * 2451545D0 -1421.3D0 (J2000 method) * 2400000.5D0 50123.2D0 (MJD method) * 2450123.5D0 0.2D0 (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 routine 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 SOFA routine iau_EPV00 (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 iau_ANP routine can then be applied, as * required, to keep the result in the conventional 0-2pi range.) * * Called: * iau_APCI13 astrometry parameters, ICRS-CIRS, 2013 * iau_ATCIQ quick ICRS to CIRS * * This revision: 2022 May 3 * * SOFA release 2023-10-11 * * Copyright (C) 2023 IAU SOFA Board. See notes at end. * *----------------------------------------------------------------------- IMPLICIT NONE DOUBLE PRECISION RC, DC, PR, PD, PX, RV, DATE1, DATE2, RI, DI, EO * Star-independent astrometry parameters DOUBLE PRECISION ASTROM(30) * - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - * The transformation parameters. CALL iau_APCI13 ( DATE1, DATE2, ASTROM, EO ) * ICRS (epoch J2000.0) to CIRS. CALL iau_ATCIQ ( RC, DC, PR, PD, PX, RV, ASTROM, RI, DI ) * Finished. *+---------------------------------------------------------------------- * * Copyright (C) 2023 * Standards of Fundamental Astronomy Board * of the International Astronomical Union. * * ===================== * SOFA Software License * ===================== * * NOTICE TO USER: * * BY USING THIS SOFTWARE YOU ACCEPT THE FOLLOWING SIX TERMS AND * CONDITIONS WHICH APPLY TO ITS USE. * * 1. The Software is owned by the IAU SOFA Board ("SOFA"). * * 2. Permission is granted to anyone to use the SOFA software for any * purpose, including commercial applications, free of charge and * without payment of royalties, subject to the conditions and * restrictions listed below. * * 3. You (the user) may copy and distribute SOFA source code to others, * and use and adapt its code and algorithms in your own software, * on a world-wide, royalty-free basis. 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