sofars 0.6.0

use super::{IauAstrom, apco13, atciq, atioq};

///  ICRS −> observed
///
///  ICRS RA,Dec to observed place.  The caller supplies UTC, site
///  coordinates, ambient air conditions and observing wavelength.
///
///  SOFA models are used for the Earth ephemeris, bias-precession-
///  nutation, Earth orientation and refraction.
///
///  This function is part of the International Astronomical Union's
///  SOFA (Standards of Fundamental Astronomy) software collection.
///
///  Status:  support function.
///
///  Given:
///  ```
///     rc,dc  double   ICRS right ascension at J2000.0 (radians, Note 1)
///     pr     double   RA proper motion (radians/year, Note 2)
///     pd     double   Dec proper motion (radians/year)
///     px     double   parallax (arcsec)
///     rv     double   radial velocity (km/s, +ve if receding)
///     utc1   double   UTC as a 2-part...
///     utc2   double   ...quasi Julian Date (Notes 3-4)
///     dut1   double   UT1-UTC (seconds, Note 5)
///     elong  double   longitude (radians, east +ve, Note 6)
///     phi    double   latitude (geodetic, radians, Note 6)
///     hm     double   height above ellipsoid (m, geodetic, Notes 6,8)
///     xp,yp  double   polar motion coordinates (radians, Note 7)
///     phpa   double   pressure at the observer (hPa = mB, Note 8)
///     tc     double   ambient temperature at the observer (deg C)
///     rh     double   relative humidity at the observer (range 0-1)
///     wl     double   wavelength (micrometers, Note 9)
///  ```
///  Returned
///  ```
///     aob    double*  observed azimuth (radians: N=0,E=90)
///     zob    double*  observed zenith distance (radians)
///     hob    double*  observed hour angle (radians)
///     dob    double*  observed declination (radians)
///     rob    double*  observed right ascension (CIO-based, radians)
///     eo     double*  equation of the origins (ERA-GST, radians)
///  ```
///  Returned (function value):
///  ```
///            int      status: +1 = dubious year (Note 4)
///                              0 = OK
///                             -1 = unacceptable date
///  ```
///
///  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 iauPmsafe before use.
///
///  2)  The proper motion in RA is dRA/dt rather than cos(Dec)*dRA/dt.
///
///  3)  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 function is that the JD day represents UTC days whether
///      the length is 86399, 86400 or 86401 SI seconds.
///
///      Applications should use the function iauDtf2d 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.
///
///  4)  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 iauDat for further details.
///
///  5)  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.
///
///  6)  The geographical coordinates are with respect to the WGS84
///      reference ellipsoid.  TAKE CARE WITH THE LONGITUDE SIGN:  the
///      longitude required by the present function is east-positive
///      (i.e. right-handed), in accordance with geographical convention.
///
///  7)  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.
///
///  8)  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.
///
///  9)  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).
///
///  10) The accuracy of the result is limited by the corrections for
///      refraction, which use a simple A*tan(z) + B*tan^3(z) model.
///      Providing the meteorological parameters are known accurately and
///      there are no gross local effects, the predicted observed
///      coordinates should be within 0.05 arcsec (optical) or 1 arcsec
///      (radio) for a zenith distance of less than 70 degrees, better
///      than 30 arcsec (optical or radio) at 85 degrees and better
///      than 20 arcmin (optical) or 30 arcmin (radio) at the horizon.
///
///      Without refraction, the complementary functions iauAtco13 and
///      iauAtoc13 are self-consistent to better than 1 microarcsecond
///      all over the celestial sphere.  With refraction included,
///      consistency falls off at high zenith distances, but is still
///      better than 0.05 arcsec at 85 degrees.
///
///  11) "Observed" Az,ZD means the position that would be seen by a
///      perfect geodetically aligned theodolite.  (Zenith distance is
///      used rather than altitude in order to reflect the fact that no
///      allowance is made for depression of the horizon.)  This is
///      related to the observed HA,Dec via the standard rotation, using
///      the geodetic latitude (corrected for polar motion), while the
///      observed HA and RA are related simply through the Earth rotation
///      angle and the site longitude.  "Observed" RA,Dec or HA,Dec thus
///      means the position that would be seen by a perfect equatorial
///      with its polar axis aligned to the Earth's axis of rotation.
///
///  12) 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.
///
///  Called:
///  ```
///     iauApco13    astrometry parameters, ICRS-observed, 2013
///     iauAtciq     quick ICRS to CIRS
///     iauAtioq     quick CIRS to observed
///  ```
pub fn atco13(
    rc: f64,
    dc: f64,
    pr: f64,
    pd: f64,
    px: f64,
    rv: f64,
    utc1: f64,
    utc2: f64,
    dut1: f64,
    elong: f64,
    phi: f64,
    hm: f64,
    xp: f64,
    yp: f64,
    phpa: f64,
    tc: f64,
    rh: f64,
    wl: f64,
) -> Result<(f64, f64, f64, f64, f64, f64), i32> {
    let astrom = &mut IauAstrom::default();
    let eo = &mut 0.0;

    /* Star-independent astrometry parameters. */
    let j = apco13(
        utc1, utc2, dut1, elong, phi, hm, xp, yp, phpa, tc, rh, wl, astrom, eo,
    );

    /* Abort if bad UTC. */
    if j.is_err() {
        return Err(j.unwrap_err());
    };

    /* Transform ICRS to CIRS. */
    let (ri, di) = atciq(rc, dc, pr, pd, px, rv, astrom);

    /* Transform CIRS to observed. */
    let (aob, zob, hob, dob, rob) = atioq(ri, di, astrom);

    /* Return values */
    Ok((aob, zob, hob, dob, rob, *eo))
}