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EULER

EULER

Name


    EULER

Purpose


    Transform between Galactic, celestial, and ecliptic coordinates.

Explanation


    Use the procedure ASTRO to use this routine interactively

Calling Sequence


      EULER, AI, BI, AO, BO, [ SELECT, /FK4, /RADIAN, SELECT = ]

Inputs


      AI - Input Longitude, scalar or vector. In DEGREES unless /RADIAN
            is set. If only two parameters are supplied, then AI and BI
            will be modified to contain the output longitude and latitude.
      BI - Input Latitude in DEGREES

Optional Input


      SELECT - Integer (1-6) specifying type of coordinate transformation.
      SELECT From To | SELECT From To
      1 RA-Dec (2000) Galactic | 4 Ecliptic RA-Dec
      2 Galactic RA-DEC | 5 Ecliptic Galactic
      3 RA-Dec Ecliptic | 6 Galactic Ecliptic
      If not supplied as a parameter or keyword, then EULER will prompt for
      the value of SELECT
      Celestial coordinates (RA, Dec) should be given in equinox J2000
      unless the /FK4 keyword is set.

Outputs


      AO - Output Longitude in DEGREES, always double precision
      BO - Output Latitude in DEGREES, always double precision

Optional Input Keyword


      /FK4 - If this keyword is set and non-zero, then input and output
            celestial and ecliptic coordinates should be given in equinox
            B1950.
      /RADIAN - if set, then all input and output angles are in radians rather
            than degrees.
      SELECT - The coordinate conversion integer (1-6) may alternatively be
              specified as a keyword

Example


      Find the Galactic coordinates of Cyg X-1 (ra=299.590315, dec=35.201604)
      IDL> ra = 299.590315d
      IDL> dec = 35.201604d
      IDL> euler,ra,dec,glong,glat,1 & print,glong,glat
            71.334990, 3.0668335

Revision History


      Written W. Landsman, February 1987
      Adapted from Fortran by Daryl Yentis NRL
      Made J2000 the default, added /FK4 keyword W. Landsman December 1998
      Add option to specify SELECT as a keyword W. Landsman March 2003
      Use less virtual memory for large input arrays W. Landsman June 2008
      Added /RADIAN input keyword W. Landsman Sep 2008



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