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      Converts Hour Angle and Declination to Horizon (alt-az) coordinates.


      Can deal with NCP/SCP singularity. Intended mainly to be used by
      program EQ2HOR

Calling Sequence

      HADEC2ALTAZ, ha, dec, lat ,alt ,az [ /WS ]


    ha - the local apparent hour angle, in DEGREES, scalar or vector
    dec - the local apparent declination, in DEGREES, scalar or vector
    lat - the local latitude, in DEGREES, scalar or vector


    alt - the local apparent altitude, in DEGREES.
    az - the local apparent azimuth, in DEGREES, all results in double

Optional Keyword Input

      /WS - Set this keyword for the output azimuth to be measured West from
            South. The default is to measure azimuth East from North.


    What were the apparent altitude and azimuth of the sun when it transited
    the local meridian at Pine Bluff Observatory (Lat=+43.07833 degrees) on
    April 21, 2002? An object transits the local meridian at 0 hour angle.
    Assume this will happen at roughly 1 PM local time (18:00 UTC).
    IDL> jdcnv, 2002, 4, 21, 18., jd ; get rough Julian date to determine
                                      ;Sun ra, dec.
    IDL> sunpos, jd, ra, dec
    IDL> hadec2altaz, 0., dec, 43.078333, alt, az
      ===> Altitude alt = 58.90
            Azimuth az = 180.0

Revision History

      Written Chris O'Dell Univ. of Wisconsin-Madison May 2002

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