SUBROUTINE iau_APCO13 ( UTC1, UTC2, DUT1, ELONG, PHI, HM, XP, YP, : PHPA, TC, RH, WL, ASTROM, EO, J ) *+ * - - - - - - - - - - - * i a u _ A P C O 1 3 * - - - - - - - - - - - * * For a terrestrial observer, prepare star-independent astrometry * parameters for transformations between ICRS and observed coordinates. * The caller supplies UTC, site coordinates, ambient air conditions and * observing wavelength, and SOFA models are used to obtain the Earth * ephemeris, CIP/CIO and refraction constants. * * The parameters produced by this routine are required in the parallax, * light deflection, aberration, and bias-precession-nutation parts of * the ICRS/CIRS transformations. * * This routine is part of the International Astronomical Union's * SOFA (Standards of Fundamental Astronomy) software collection. * * Status: support routine. * * Given: * UTC1 d UTC as a 2-part... * UTC2 d ...quasi Julian Date (Notes 1,2) * DUT1 d UT1-UTC (seconds, Note 3) * ELONG d longitude (radians, east +ve, Note 4) * PHI d latitude (geodetic, radians, Note 4) * HM d height above ellipsoid (m, geodetic, Notes 4,6) * XP,YP d polar motion coordinates (radians, Note 5) * PHPA d pressure at the observer (hPa = mB, Note 6) * TC d ambient temperature at the observer (deg C) * RH d relative humidity at the observer (range 0-1) * WL d wavelength (micrometers, Note 7) * * Returned: * ASTROM d(30) star-independent astrometry parameters: * (1) PM time interval (SSB, Julian years) * (2-4) SSB to observer (vector, au) * (5-7) Sun to observer (unit vector) * (8) distance from Sun to observer (au) * (9-11) v: barycentric observer velocity (vector, c) * (12) sqrt(1-|v|^2): reciprocal of Lorenz factor * (13-21) bias-precession-nutation matrix * (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) * EO d equation of the origins (ERA-GST) * J i status: +1 = dubious year (Note 2) * 0 = OK * -1 = unacceptable date * * Notes: * * 1) UTC1+UTC2 is quasi Julian Date (see Note 2), apportioned in any * convenient way between the two arguments, for example where UTC1 * is the Julian Day Number and UTC2 is the fraction of a day. * * However, JD cannot unambiguously represent UTC during a leap * second unless special measures are taken. The convention in the * present routine is that the JD day represents UTC days whether * the length is 86399, 86400 or 86401 SI seconds. * * Applications should use the routine iau_DTF2D to convert from * calendar date and time of day into 2-part quasi Julian Date, as * it implements the leap-second-ambiguity convention just * described. * * 2) The warning status "dubious year" flags UTCs that predate the * introduction of the time scale or that are too far in the * future to be trusted. See iau_DAT for further details. * * 3) UT1-UTC is tabulated in IERS bulletins. It increases by exactly * one second at the end of each positive UTC leap second, * introduced in order to keep UT1-UTC within +/- 0.9s. n.b. This * practice is under review, and in the future UT1-UTC may grow * essentially without limit. * * 4) 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. * * 5) 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. * * 6) If hm, the height above the ellipsoid of the observing station * in meters, is not known but phpa, the pressure in hPa (=mB), is * available, an adequate estimate of hm can be obtained from the * expression * * hm = -29.3 * tsl * log ( phpa / 1013.25 ); * * where tsl is the approximate sea-level air temperature in K * (See Astrophysical Quantities, C.W.Allen, 3rd edition, section * 52). Similarly, if the pressure phpa is not known, it can be * estimated from the height of the observing station, hm, as * follows: * * phpa = 1013.25 * exp ( -hm / ( 29.3 * tsl ) ); * * Note, however, that the refraction is nearly proportional to * the pressure and that an accurate phpa value is important for * precise work. * * 7) The argument WL specifies the observing wavelength in * micrometers. The transition from optical to radio is assumed to * occur at 100 micrometers (about 3000 GHz). * * 8) 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. * * 9) In cases where the caller wishes to supply his own Earth * ephemeris, Earth rotation information and refraction constants, * the routine iau_APCO can be used instead of the present routine. * * 10) 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. * * 11) The context array ASTROM produced by this routine is used by * iau_ATIOQ, iau_ATOIQ, iau_ATCIQ* and iau_ATICQ*. * * Called: * iau_UTCTAI UTC to TAI * iau_TAITT TAI to TT * iau_UTCUT1 UTC to UT1 * iau_EPV00 Earth position and velocity * iau_PNM06A classical NPB matrix, IAU 2006/2000A * iau_BPN2XY extract CIP X,Y coordinates from NPB matrix * iau_S06 the CIO locator s, given X,Y, IAU 2006 * iau_ERA00 Earth rotation angle, IAU 2000 * iau_SP00 the TIO locator s', IERS 2000 * iau_REFCO refraction constants for given ambient conditions * iau_APCO astrometry parameters, ICRS-observed * iau_EORS equation of the origins, given NPB matrix and s * * This revision: 2013 December 5 * * SOFA release 2013-12-02 * * Copyright (C) 2013 IAU SOFA Board. See notes at end. * *----------------------------------------------------------------------- IMPLICIT NONE DOUBLE PRECISION UTC1, UTC2, DUT1, ELONG, PHI, HM, XP, YP, : PHPA, TC, RH, WL, ASTROM(30), EO INTEGER J INTEGER JS, JW DOUBLE PRECISION TAI1, TAI2, TT1, TT2, UT11, UT12, : EHPV(3,2), EBPV(3,2), R(3,3), X, Y, S, THETA, : SP, REFA, REFB DOUBLE PRECISION iau_S06, iau_ERA00, iau_SP00, iau_EORS * - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - * UTC to other time scales. CALL iau_UTCTAI ( UTC1, UTC2, TAI1, TAI2, JS ) IF ( JS.LT.0 ) GO TO 9 CALL iau_TAITT ( TAI1, TAI2, TT1, TT2, JS ) CALL iau_UTCUT1 ( UTC1, UTC2, DUT1, UT11, UT12, JS ) IF ( JS.LT.0 ) GO TO 9 * Earth barycentric & heliocentric position/velocity (au, au/d). CALL iau_EPV00 ( TT1, TT2, EHPV, EBPV, JW ) * Form the equinox based BPN matrix, IAU 2006/2000A. CALL iau_PNM06A ( TT1, TT2, R ) * Extract CIP X,Y. CALL iau_BPN2XY ( R, X, Y ) * Obtain CIO locator s. S = iau_S06 ( TT1, TT2, X, Y ) * Earth rotation angle. THETA = iau_ERA00 ( UT11, UT12 ) * TIO locator s'. SP = iau_SP00 ( TT1, TT2 ) * Refraction constants A and B. CALL iau_REFCO ( PHPA, TC, RH, WL, REFA, REFB ) * Compute the star-independent astrometry parameters. CALL iau_APCO ( TT1, TT2, EBPV, EHPV, X, Y, S, THETA, : ELONG, PHI, HM, XP, YP, SP, REFA, REFB, : ASTROM ) * Equation of the origins. EO = iau_EORS ( R, S ) * Return the status. 9 CONTINUE J = JS * Finished. *+---------------------------------------------------------------------- * * Copyright (C) 2013 * 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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The provision of any version of the SOFA software under the terms * and conditions specified herein does not imply that future * versions will also be made available under the same terms and * conditions. * * In any published work or commercial product which uses the SOFA * software directly, acknowledgement (see www.iausofa.org) is * appreciated. * * Correspondence concerning SOFA software should be addressed as * follows: * * By email: sofa@ukho.gov.uk * By post: IAU SOFA Center * HM Nautical Almanac Office * UK Hydrographic Office * Admiralty Way, Taunton * Somerset, TA1 2DN * United Kingdom * *----------------------------------------------------------------------- END