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 2019-07-22
*
* Copyright (C) 2019 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) 2019
* 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. That portion of your
* distribution that does not consist of intact and unchanged copies
* of SOFA source code files is a "derived work" that must comply
* with the following requirements:
*
* a) Your work shall be marked or carry a statement that it
* (i) uses routines and computations derived by you from
* software provided by SOFA under license to you; and
* (ii) does not itself constitute software provided by and/or
* endorsed by SOFA.
*
* b) The source code of your derived work must contain descriptions
* of how the derived work is based upon, contains and/or differs
* from the original SOFA software.
*
* c) The names of all routines in your derived work shall not
* include the prefix "iau" or "sofa" or trivial modifications
* thereof such as changes of case.
*
* d) The origin of the SOFA components of your derived work must
* not be misrepresented; you must not claim that you wrote the
* original software, nor file a patent application for SOFA
* software or algorithms embedded in the SOFA software.
*
* e) These requirements must be reproduced intact in any source
* distribution and shall apply to anyone to whom you have
* granted a further right to modify the source code of your
* derived work.
*
* Note that, as originally distributed, the SOFA software is
* intended to be a definitive implementation of the IAU standards,
* and consequently third-party modifications are discouraged. All
* variations, no matter how minor, must be explicitly marked as
* such, as explained above.
*
* 4. You shall not cause the SOFA software to be brought into
* disrepute, either by misuse, or use for inappropriate tasks, or
* by inappropriate modification.
*
* 5. The SOFA software is provided "as is" and SOFA makes no warranty
* as to its use or performance. SOFA does not and cannot warrant
* the performance or results which the user may obtain by using the
* SOFA software. SOFA makes no warranties, express or implied, as
* to non-infringement of third party rights, merchantability, or
* fitness for any particular purpose. In no event will SOFA be
* liable to the user for any consequential, incidental, or special
* damages, including any lost profits or lost savings, even if a
* SOFA representative has been advised of such damages, or for any
* claim by any third party.
*
* 6. 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