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      SUBROUTINE slOAPQ (TYPE, OB1, OB2, AOPRMS, RAP, DAP)

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      O A P Q
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  Quick observed to apparent place

  Given:
     TYPE   c*(*)  type of coordinates - 'R', 'H' or 'A' (see below)
     OB1    d      observed Az, HA or RA (radians; Az is N=0,E=90)
     OB2    d      observed ZD or Dec (radians)
     AOPRMS d(14)  star-independent apparent-to-observed parameters:

       (1)      geodetic latitude (radians)
       (2,3)    sine and cosine of geodetic latitude
       (4)      magnitude of diurnal aberration vector
       (5)      height (HM)
       (6)      ambient temperature (T)
       (7)      pressure (P)
       (8)      relative humidity (RH)
       (9)      wavelength (WL)
       (10)     lapse rate (TLR)
       (11,12)  refraction constants A and B (radians)
       (13)     longitude + eqn of equinoxes + sidereal DUT (radians)
       (14)     local apparent sidereal time (radians)

  Returned:
     RAP    d      geocentric apparent right ascension
     DAP    d      geocentric apparent declination

  Notes:

  1)  Only the first character of the TYPE argument is significant.
      'R' or 'r' indicates that OBS1 and OBS2 are the observed Right
      Ascension and Declination;  'H' or 'h' indicates that they are
      Hour Angle (West +ve) and Declination;  anything else ('A' or
      'a' is recommended) indicates that OBS1 and OBS2 are Azimuth
      (North zero, East is 90 deg) and zenith distance.  (Zenith
      distance is used rather than elevation in order to reflect the
      fact that no allowance is made for depression of the horizon.)

  2)  The accuracy of the result is limited by the corrections for
      refraction.  Providing the meteorological parameters are
      known accurately and there are no gross local effects, the
      predicted apparent RA,Dec should be within about 0.1 arcsec
      for a zenith distance of less than 70 degrees.  Even at a
      topocentric zenith distance of 90 degrees, the accuracy in
      elevation should be better than 1 arcmin;  useful results
      are available for a further 3 degrees, beyond which the
      slRFRO routine returns a fixed value of the refraction.
      The complementary routines slAOP (or slAOPQ) and slOAP
      (or slOAPQ) are self-consistent to better than 1 micro-
      arcsecond all over the celestial sphere.

  3)  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.

  5)  "Observed" Az,El means the position that would be seen by a
      perfect theodolite located at the observer.  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 local
      apparent ST.  "Observed" RA,Dec or HA,Dec thus means the
      position that would be seen by a perfect equatorial located
      at the observer and with its polar axis aligned to the
      Earth's axis of rotation (n.b. not to the refracted pole).
      By removing from the observed place the effects of
      atmospheric refraction and diurnal aberration, the
      geocentric apparent RA,Dec is obtained.

  5)  Frequently, mean rather than apparent RA,Dec will be required,
      in which case further transformations will be necessary.  The
      slAMP etc routines will convert the apparent RA,Dec produced
      by the present routine into an "FK5" (J2000) mean place, by
      allowing for the Sun's gravitational lens effect, annual
      aberration, nutation and precession.  Should "FK4" (1950)
      coordinates be needed, the routines slFK54 etc will also
      need to be applied.

  6)  To convert to apparent RA,Dec the coordinates read from a
      real telescope, corrections would have to be applied for
      encoder zero points, gear and encoder errors, tube flexure,
      the position of the rotator axis and the pointing axis
      relative to it, non-perpendicularity between the mounting
      axes, and finally for the tilt of the azimuth or polar axis
      of the mounting (with appropriate corrections for mount
      flexures).  Some telescopes would, of course, exhibit other
      properties which would need to be accounted for at the
      appropriate point in the sequence.

  7)  The star-independent apparent-to-observed-place parameters
      in AOPRMS may be computed by means of the slAOPA routine.
      If nothing has changed significantly except the time, the
      slAOPT routine may be used to perform the requisite
      partial recomputation of AOPRMS.

  8) The azimuths etc used by the present routine are with respect
     to the celestial pole.  Corrections from the terrestrial pole
     can be computed using slPLMO.

  Called:  slDS2C, slDC2S, slRFRO, slDA2P

  P.T.Wallace   Starlink   23 June 1997

  Copyright (C) 1996 Rutherford Appleton Laboratory
  Copyright (C) 1995 Association of Universities for Research in Astronomy Inc.

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