While the A-series was successfully sold, a larger and more advanced model was built, the "Space Transit Projector", STP. It is a departure from the usual design. Complete programming is possible with a built-in digital computer. Light is emitted through over 4000 small holes, and over 200 larger ones which contain lenses and filters, to represent the brighter stars. The source is a high pressure Xenon gas arc lamps placed within the star hemispheres. Planetary motions differ from the Zeiss concept in that they are derived from electrical analogs instead of gearworks. The weight is less than 500 kg. The first instrument was installed in early 1973 in San Diego, afterwards only 11 pieces were built. The Miami Science Museum in Florida is one of the last planetariums still employing it.