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Abteilung Astronomie

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EQPOLE_GRID Source code in eqpole_grid.pro

EQPOLE_GRID

Name
       EQPOLE_GRID
Purpose
       Produce an equal area polar projection grid overlay
Explanation
       Grid is written on the current graphics device using the equal area
       polar projection.   EQPOLE_GRID assumes that the output plot
       coordinates span the x and y ranges of -90 to 90 for a region that
       covers the equator to the chosen pole. The grid is assumed to go from
       the equator to the chosen pole.
Calling Sequence
       EQPOLE_GRID[,DLONG,DLAT,[/SOUTHPOLE, LABEL = , /NEW, _EXTRA=]
Input Parameters
       DLONG   = Optional input longitude line spacing in degrees. If left
                 out, defaults to 30.
       DLAT    = Optional input lattitude line spacing in degrees. If left
                 out, defaults to 30.
Keyword Parameters
       /SOUTHPOLE       = Optional flag indicating that the output plot is
                         to be centered on the south rather than the north
                         pole.
       LABEL           = Optional flag for creating labels on the output
                         grid on the prime meridian and the equator for
                         lattitude and longitude lines. If set =2, then
                         the longitude lines are labeled in hours and minutes.
       CHARSIZE       = If /LABEL is set, then CHARSIZE specifies the size
                         of the label characters (passed to XYOUTS)
       CHARTHICK     =  If /LABEL is set, then CHARTHICK specifies the
                         thickness of the label characters (passed to XYOUTS)
       /NEW          =   If this keyword is set, then EQPOLE_GRID will create
                         a new plot, rather than overlay an existing plot.
       Any valid keyword to OPLOT such as COLOR, LINESTYLE, THICK can be
       passed to AITOFF_GRID (though the _EXTRA facility) to to specify the
       color, style, or thickness of the grid lines.
Output Parameters
       Draws grid lines on current graphics device.
Example
       Create a labeled equal area projection grid of the Galaxy, centered on
       the South pole, and overlay stars at specified Galactic longitudes,
       glong and latitudes, glat
       IDL> eqpole_grid,/label,/new,/south       ;Create labeled grid
       IDL> eqpole, glong, glat, x,y      ;Convert to X,Y coordinates
       IDL> plots,x,y,psym=2              ;Overplot "star" positions.
Copyright
       Copyright 1992, The Regents of the University of California. This
       software was produced under U.S. Government contract (W-7405-ENG-36)
       by Los Alamos National Laboratory, which is operated by the
       University of California for the U.S. Department of Energy.
       The U.S. Government is licensed to use, reproduce, and distribute
       this software. Neither the Government nor the University makes
       any warranty, express or implied, or assumes any liability or
       responsibility for the use of this software.
Revision History
       J. Bloch        1.4     10/28/92
       Converted to IDL V5.0   W. Landsman   September 1997
       Create default plotting coords, if needed   W. Landsman  August 2000
       Added _EXTRA, CHARTHICK, CHARSIZE keywords  W. Landsman  March 2001

Last modified by pro2html on 2001 April 26 at 03:10 UTC

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