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# atccq

erfa.atccq(rc, dc, pr, pd, px, rv, astrom)

  Quick transformation of a star’s ICRS catalog entry (epoch J2000.0) into ICRS astrometric place, given precomputed star-independent astrometry parameters.

  Parameters:
    rc double array
    dc double array
    pr double array
    pd double array
    px double array
    rv double array
    astrom eraASTROM array
  Returns:
    ra double array
    da double array

  Notes

  Wraps ERFA function `eraAtccq`. The ERFA documentation is:

      - - - - - - - - -
       e r a A t c c q
      - - - - - - - - -

      Quick transformation of a star's ICRS catalog entry (epoch J2000.0)
      into ICRS astrometric place, given precomputed star-independent
      astrometry parameters.

      Use of this function is appropriate when efficiency is important and
      where many star positions are to be transformed for one date.  The
      star-independent parameters can be obtained by calling one of the
      functions eraApci[13], eraApcg[13], eraApco[13] or eraApcs[13].

      If the parallax and proper motions are zero the transformation has
      no effect.

      Given:
         rc,dc  double     ICRS RA,Dec at J2000.0 (radians)
         pr     double     RA proper motion (radians/year, Note 3)
         pd     double     Dec proper motion (radians/year)
         px     double     parallax (arcsec)
         rv     double     radial velocity (km/s, +ve if receding)
         astrom eraASTROM* star-independent astrometry parameters:
          pmt    double       PM time interval (SSB, Julian years)
          eb     double[3]    SSB to observer (vector, au)
          eh     double[3]    Sun to observer (unit vector)
          em     double       distance from Sun to observer (au)
          v      double[3]    barycentric observer velocity (vector, c)
          bm1    double       sqrt(1-|v|^2): reciprocal of Lorenz factor
          bpn    double[3][3] bias-precession-nutation matrix
          along  double       longitude + s' (radians)
          xpl    double       polar motion xp wrt local meridian (radians)
          ypl    double       polar motion yp wrt local meridian (radians)
          sphi   double       sine of geodetic latitude
          cphi   double       cosine of geodetic latitude
          diurab double       magnitude of diurnal aberration vector
          eral   double       "local" Earth rotation angle (radians)
          refa   double       refraction constant A (radians)
          refb   double       refraction constant B (radians)

      Returned:
         ra,da  double          ICRS astrometric RA,Dec (radians)

      Notes:

      1) All the vectors are with respect to BCRS axes.

      2) 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 eraPmsafe before use.

      3) The proper motion in RA is dRA/dt rather than cos(Dec)*dRA/dt.

      Called:
         eraPmpx      proper motion and parallax
         eraC2s       p-vector to spherical
         eraAnp       normalize angle into range 0 to 2pi

      This revision:   2021 April 18

      Copyright (C) 2013-2023, NumFOCUS Foundation.
      Derived, with permission, from the SOFA library.  See notes at end of file.