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The XYEllipse form ()
plots an ellipse (or rectangle, triangle, or other similar figure)
defined by two principal radii and an optional angle of rotation,
the socalled position angle.
This angle, if specified, is in degrees and gives the angle
counterclockwise from the horizontal axis to the first principal radius.
Example XYEllipse plot
XYEllipse form configuration panel
The configuration options are:

Shading Mode
 See Appendix A.4.6.

Primary Radius, Secondary Radius
 The two principal radii for the ellipse, in the same units as the
position coordinates.
It doesn't matter whether the primary is larger than the secondary.
If the Secondary Radius field is left blank, it is assumed to equal
the Primary Radius field, i.e. the ellipses are circles.

Orientation
 Position angle in degrees.
This is the angle anticlockwise from the X axis
to the primary radius.
If the value is missing (either this field not filled in or blank in
the data) it is considered to be zero.

Ellipse
 Ellipse graphical representation, selected from a range of options
(includes also rectangles, crosses etc).

Scale
 Changes the factor by which all ellipse sizes are scaled.
If the ellipses are too small, slide it right, if they are too big,
slide it left. The slider scale is logarithmic.
Alternatively, enter a fixed value in the text field.

Auto Scale
 If selected, this option will determine the default ellipse scale size
from the data  it will fix it so that the largest ellipses are a few
tens of pixels long by default.
That scaling can then be adjusted using the Scale slider.
If unselected, then the default position of the Scale slider corresponds
to the actual positions given by the submitted ellipse radii coordinates.
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Next: SkyEllipse Form
Up: Plot Forms
Previous: Error Bars Form
TOPCAT  Tool for OPerations on Catalogues And Tables
Starlink User Note253
TOPCAT web page:
http://www.starlink.ac.uk/topcat/
Author email:
m.b.taylor@bristol.ac.uk
Mailing list:
topcatuser@jiscmail.ac.uk