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=]
Inputs
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.
Input Keywords
/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.
Outputs
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 Notice
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.
Author And Modifications
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