Telescope & Building
The telescope at the Three College Observatory is a Cassegrain reflecting telescope. The mirror diameter is 0.81 meters (32 inches). This characteristic of a telescope is perhaps the most important factor in determining the telescope’s effectiveness as a research instrument since it determines the amount of light it can collect, and hence the effectiveness of the telescope in detecting very dim or very distant objects.
The telescope at the Three College Observatory can collect approximately 26,000 times as much light as the human eye.
The telescope is the largest telescope in North Carolina, and one of the largest in the southeastern United States. The only larger telescopes at dark sky locations include the 41-inch Fan Mountain telescope operated by the University of Virginia, and the 36-inch telescope operated by the University of Florida.
The f/13.5 telescope was constructed in 1979 by Sigma Research, Inc., of Richland, WA and installed at the Three College Observatory in May 1981. The fork-mounted equatorial design uses a friction drive for both right ascension and declination axes, and is capable of tracking along both axes. The telescope utilizes a Cer-Vit primary mirror and Ritchey-Chretien optics. The usable photographic field size is 3.75 inches in diameter at a plate scale of 18.8 arc seconds/mm. The telescope weighs 9000 lbs. and is mounted on a 7 x 8 x 10 foot concrete pier weighing 50 tons.
The telescope is equipped with an f/10 6-inch refractive finder telescope (with a 1.3 degree field) designed and built by Duncan Davidson of Seattle, Washington. Instrumentation for the telescope includes a photographic camera utilizing 4 x 5 inch glass plates, an archaic digitized ISIT low light level video camera, an echelle spectrograph, and a state-of-the-art CCD Video Camera.
The telescope’s motion and positioning is controlled by the PC-TCS/DCS DC Servo Motor Telescope Control System from COMSOFT, 1552 West Chapala Drive, Tucson, Arizona 85704 (520) 360-2078
The telescope shown above is a Ritchey-Chretien cassegrain telescope built by Sigma Research, Inc., Richland, Washington. The telescope tube measures approximately 3 meters in length, and has a diameter of slightly less than 1 meter. The clear aperture of the mirror is 0.81 meters.
The dome pictured here is a 24-foot diameter rotatable aluminum dome constructed by Ash Manufacturing Company, Plainfield, Illinois.
The observatory contains a circular observing room which is unheated, a small classroom, a darkroom and lavatory facilities. The wooded location, in central Alamance County, was selected because it is far enough from the interstate highway corridor and from Greensboro and Burlington to provide reasonably dark skies.
The 0.81-meter Three College Observatory was built by Sigma Research Corporation of Richland, Washington. The design of this telescope is similar to the design of other telescopes built by Sigma at about the same time, and is similar to an earlier telescope design that was used for the astrometric reflecting telescope at the Unviversity of Virginia.
Visit some of these observatories through the following links:
University of Virginia, Fan Mountain Observatory, Charlottesville, Va