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APPARATUS

The surface of the water forms a paraboloid.  If the liquid were mercury, the surface would serve as a concave mirror.  Instead add some dark dye to the water to reduce internal reflections.

The shape of the surface is given by z = (ω ²/2g)r².  This is a parabola with focal length f = g/2ω ².

NO TES

Use glitter to make flow more visible.

Use glycerine instead of water for a more stable surface.  

Use an arrow light source to investigate the images formed.  

This demonstration can be set up in the display case.

The Astrophysical Journal, 346:  L41-L44.

AJP 58(3),280