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HADEC2ALTAZ Source code in hadec2altaz.pro

HADEC2ALTAZ

Name
     HADEC2ALTAZ
Purpose
      Converts Hour Angle and Declination to Horizon (alt-az) coordinates.
Explanation
      Can deal with NCP/SCP singularity.    Intended mainly to be used by
      program EQ2HOR
Calling Sequence
      HADEC2ALTAZ, ha, dec, lat ,alt ,az [ /WS ]
Input Parameters
     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
Output Parameters
     alt - the local apparent altitude, in DEGREES.
     az  - the local apparent azimuth, in DEGREES, all results in double
           precision
Keyword Parameters
      /WS - Set this keyword for the output azimuth to be measured West from
            South.    The default is to measure azimuth East from North.
Example
     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

Last modified by pro2html on 2002 June 14 at 03:22 UTC

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Jörn Wilms (wilms@astro.uni-tuebingen.de)
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