Focal Plane Plug Plate, Sloan Sky Survey

This aluminum "plug plate" is typical of those used at the focal plane of the Sloan Survey telescope at the Apache Point Observatory in New Mexico. This wide-field reflecting telescope has been cataloging hundreds of millions of celestial objects in the visible sky and has also been recording millions of spectra of galaxies. To capture many spectra at once, a metal plate is made with hundreds (up to 640) of holes that are precisely positioned to correspond to the positions of objects to be studied in the field of the telescope. This is then placed in the focal plane and optical fibers are plugged into each hole to capture the light from a single object and relay it to a spectrograph that records all 640 channels of informaiton at once. A different plate was built for each section of the sky. This plate was donated to NASM in 2001 by The Astrophysical Research Consortium and is now on display in the Explore the Universe gallery.