Spherical plot window
The spherical plot window draws 3-dimensional scatter plots
of datasets from one or more tables on spherical polar axes,
so it's suitable for displaying the position of coordinates on
the sky or some other spherical coordinate system, such as the
surface of a planet or the sun.
You can display it using the Sphere () button
in the Control Window's toolbar.
In most respects this window works like the 3D Plot window, but it uses spherical polar axes rather than Cartesian ones, You have to fill in the dataset selector at the bottom with longitude- and latitude-type coordinates from the table. Selectors are included to indicate the units of those coordinates. If TOPCAT can locate columns in the table which appear to represent Right Ascension and Declination, these will be filled in automatically. If only these two are filled in, then the points will be plotted on the surface of the unit sphere - this is suitable if you just want to inspect the positions of a set of objects in the sky. You can optionally fill in the Radius selector as well. If you do this, then points will be plotted on the interior of the sphere, at a distance from the centre given by the value of the radial coordinate.
Rotation, subset creation, fogging, marker customisation and toolbar actions are all as for the Cartesian 3D plot window - see Appendix A.4.5.
Zooming is also possible. You can zoom in around the
centre of the plot so that the viewing window only covers the middle.
This resembles the Axis Zoom in some of the 2-d plots,
but in this case the active region is to the right of the plot where
the legends appear. Drag the mouse down to zoom in or up to zoom
out on this part of the window.
When zoomed you can use the
Subset From Visible () toolbar button
to define a new Row Subset consisting only of the
points which are currently visible.
See Appendix A.4.1.3 for more explanation.