SUBROUTINE iau_APIO ( SP, THETA, ELONG, PHI, HM, XP, YP, : REFA, REFB, ASTROM ) *+ * - - - - - - - - - * i a u _ A P I O * - - - - - - - - - * * For a terrestrial observer, prepare star-independent astrometry * parameters for transformations between CIRS and observed coordinates. * The caller supplies the Earth orientation information and the * refraction constants as well as the site coordinates. * * This routine is part of the International Astronomical Union's * SOFA (Standards of Fundamental Astronomy) software collection. * * Status: support routine. * * Given: * SP d the TIO locator s' (radians, Note 1) * THETA d Earth rotation angle (radians) * ELONG d longitude (radians, east +ve, Note 2) * PHI d geodetic latitude (radians, Note 2) * HM d height above ellipsoid (m, geodetic Note 2) * XP,YP d polar motion coordinates (radians, Note 3) * REFA d refraction constant A (radians, Note 4) * REFB d refraction constant B (radians, Note 4) * * Returned: * ASTROM d(30) star-independent astrometry parameters: * (1) unchanged * (2-4) unchanged * (5-7) unchanged * (8) unchanged * (9-11) unchanged * (12) unchanged * (13-21) unchanged * (22) longitude + s' (radians) * (23) polar motion xp wrt local meridian (radians) * (24) polar motion yp wrt local meridian (radians) * (25) sine of geodetic latitude * (26) cosine of geodetic latitude * (27) magnitude of diurnal aberration vector * (28) "local" Earth rotation angle (radians) * (29) refraction constant A (radians) * (30) refraction constant B (radians) * * Notes: * * 1) SP, the TIO locator s', is a tiny quantity needed only by the most * precise applications. It can either be set to zero or predicted * using the SOFA routine iau_SP00. * * 2) The geographical coordinates are with respect to the WGS84 * reference ellipsoid. TAKE CARE WITH THE LONGITUDE SIGN: the * longitude required by the present routine is east-positive * (i.e. right-handed), in accordance with geographical convention. * * 3) The polar motion XP,YP can be obtained from IERS bulletins. The * values are the coordinates (in radians) of the Celestial * Intermediate Pole with respect to the International Terrestrial * Reference System (see IERS Conventions 2003), measured along the * meridians 0 and 90 deg west respectively. For many applications, * XP and YP can be set to zero. * * Internally, the polar motion is stored in a form rotated onto the * local meridian. * * 4) The refraction constants REFA and REFB are for use in a * dZ = A*tan(Z)+B*tan^3(Z) model, where Z is the observed * (i.e. refracted) zenith distance and dZ is the amount of * refraction. * * 5) It is advisable to take great care with units, as even unlikely * values of the input parameters are accepted and processed in * accordance with the models used. * * 6) In cases where the caller does not wish to provide the Earth * rotation information and refraction constants, the routine * iau_APIO13 can be used instead of the present routine. This * starts from UTC and weather readings etc. and computes suitable * values using other SOFA routines. * * 7) This is one of several routines that inserts into the ASTROM * array star-independent parameters needed for the chain of * astrometric transformations ICRS <-> GCRS <-> CIRS <-> observed. * * The various routines support different classes of observer and * portions of the transformation chain: * * routines observer transformation * * iau_APCG iau_APCG13 geocentric ICRS <-> GCRS * iau_APCI iau_APCI13 terrestrial ICRS <-> CIRS * iau_APCO iau_APCO13 terrestrial ICRS <-> observed * iau_APCS iau_APCS13 space ICRS <-> GCRS * iau_APER iau_APER13 terrestrial update Earth rotation * iau_APIO iau_APIO13 terrestrial CIRS <-> observed * * Those with names ending in "13" use contemporary SOFA 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. * * 8) The context array ASTROM produced by this routine is used by * iau_ATIOQ and iau_ATOIQ. * * Called: * iau_PVTOB position/velocity of terrestrial station * iau_APER astrometry parameters: update ERA * * This revision: 2013 September 25 * * SOFA release 2016-05-03 * * Copyright (C) 2016 IAU SOFA Board. See notes at end. * *----------------------------------------------------------------------- IMPLICIT NONE DOUBLE PRECISION SP, THETA, ELONG, PHI, HM, XP, YP, REFA, REFB, : ASTROM(30) * Speed of light (m/s) DOUBLE PRECISION CMPS PARAMETER ( CMPS = 299792458D0 ) DOUBLE PRECISION SL, CL, PV(3,2) * - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - * Longitude with adjustment for TIO locator s'. ASTROM(22) = ELONG + SP * Polar motion, rotated onto the local meridian. SL = SIN(ASTROM(22)) CL = COS(ASTROM(22)) ASTROM(23) = XP*CL - YP*SL ASTROM(24) = XP*SL + YP*CL * Functions of latitude. ASTROM(25) = SIN(PHI) ASTROM(26) = COS(PHI) * Observer's geocentric position and velocity (m, m/s, CIRS). CALL iau_PVTOB ( ELONG, PHI, HM, XP, YP, SP, THETA, PV ) * Magnitude of diurnal aberration vector. ASTROM(27) = SQRT ( PV(1,2)*PV(1,2) + PV(2,2)*PV(2,2) ) / CMPS * Refraction constants. ASTROM(29) = REFA ASTROM(30) = REFB * Local Earth rotation angle. CALL iau_APER ( THETA, ASTROM ) * Finished. *+---------------------------------------------------------------------- * * Copyright (C) 2016 * 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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