You are here

Photoelectric Photometer Head, 1.3-m Telescope, Kitt Peak Observatory


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 an original photometer head that formed part of a semi-automated photoelectric photometer built and used at the Kitt Peak National Observatory in the 1960s. This photometer head contains a series of differently sized apertures and filters that could be positioned in the incoming light beam by computer control making it possible to use the telescope system remotely. Once the light beam was isolated by the entrance aperture and filter, it was sent to a photomultiplier tube in another chamber attached below the box. Various different photomultiplier tubes (visual, infrared, etc) were housed in these "cold boxes." Two examples were acquired with the head: the "Red Box" (Catalogue #20000791001) and the "Oke Box" (Catalogue #20000791002).

The photometer was used on various telescopes at KPNO to measure the intensity of the light gathered from point-like sources such as stars and the nuclei of galaxies. It was donated by the Observatory to NASM in 2000. It is now on display in the Explore the Universe gallery.

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 Kitt Peak National Observatory


  • Various metals
  • Electronics


3-D: 53.3 x 50.8 x 17.8cm (21 x 20 x 7 in.)

Country of Origin

United States of America



Inventory Number