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Camera, Prime focus spectrograph, f / 0.5


Display Status:

This object is on display in the Explore the Universe exhibition at the National Air and Space Museum in Washington, DC.

Collection Item Summary:

This is one of two interchangeable cameras used with the Prime Focus Spectrograph of the 200-inch Hale Telescope at Palomar. The field flattening lens of this f / 0.5 solid Schmidt-type camera is made from diamond and the solid Schmidt is made of quartz. This instrument was designed primarily to determine the spectra of faint extragalactic objects. Called either the prime focus spectrograph or the nebular spectrograph fopr the 200-inch telescope, it was designed by Rudolph Minkowski and built at the California Institute of Technology in the late 1940s. The instrument remained in use from 1951 through 1973, providing a wealth of data on the redshift of distant galaxies, on white dwarf stars, and on the nature of radio galaxies, found to be optically stellar and hence called quasi-stellar radio sources, or quasars.

This is the faster of the two cameras and was designed to work at the practical limit for optical systems in that day. This instrument assembly was donated to NASM by the California Institute of Technology in 1998. It is now on display in the Explore the Universe gallery. In the accesison process, the Museum conducted video interviews with two astronomers who had intimate knowledge of the device.

Collection Item Long Description:

Data Source

National Air and Space Museum


Do not reproduce without permission from the Smithsonian Institution, National Air and Space Museum

Credit Line

Gift of the California Institute of Technology Palomar Observatory. No restrictions.


Overall - aluminum, glass and mixed metals


3-D (Closed): 18 × 18 × 14cm (7 1/16 × 7 1/16 × 5 1/2 in.)

Country of Origin

United States of America



Inventory Number


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