The Universe in the Classroom

Making Your Own Astronomical Camera

Tracking the Sky

In its simplest form, a barndoor tracker consists of two pieces of wood which are hinged together. A camera mounted on the upper piece and the hinge connecting the two pieces is directed toward the star Polaris, at the celestial north pole. A simple screw is turned continuously by hand to push the two pieces of wood apart to compensate precisely for Earth’s rotation. In essence, you have an equatorial telescope mount for your camera to track the stars anywhere in the sky. The tracked star images will be crisp pinpoints and you will get the full benefit of the light-collecting power of your camera. The trick is to locate the screw at a particular distance from the hinge so you can turn it once per minute and achieve precise tracking.

barndoor trackers
Two barndoor trackers with disposable cameras mounted on top. The tracker to the lower left is the simple type used by McCarthy in his classrooms. The camera itself can easily be mounted on an adjustable post to point anywhere in the sky. Students turn the lever one turn per minute to track at the sidereal rate. The tracker at the upper right belongs to John Waack of the Steward Observatory staff. It shows more customization and woodworking skill but still operates on the same principle. Photo courtesy of the authors.


Astronomy Camp for All Ages

Kuiper and Schmidt telescopes
Astronomy Campers use the research telescopes and equipment at the mountain-top observatories on Mt. Lemmon north of Tucson, Arizona. Shown here are the 1.54 meter Kuiper telescope (left) and the 0.4 meter Schmidt telescope. This picture shows the trails of stars seen in a time exposure looking toward the north celestial pole. Photo courtesy of Jeff Regester.

From the dark-sky environment at the Catalina Observatories atop scenic Mt. Lemmon near Tucson, Arizona, campers of all ages explore the heavens with large telescopes and experience the joys of scientific inquiry. Astronomy Camp, sponsored by the University of Arizona’s Alumni Association, offers all "Campers" an opportunity to experience the Universe in a new and exciting way. Teenage students gain a cosmic perspective of Earth and themselves, examine career alternatives, and reinforce school lessons through real scientific and engineering applications. Adults get away from normal routines and pose questions of a lifetime.

At night, Campers observe celestial objects under a dark sky using the 40-inch and 60-inch telescopes on Mt. Lemmon and the 16-inch Schmidt and 61-inch telescopes on nearby Mt. Bigelow. Campers become astronomers, operating research telescopes, keeping nighttime hours, interacting with leading scientists, and interpreting their own observations. Astronomy is about exploration, and Astronomy Camp fosters that philosophy.

Campers have an amazing array of unique tools to help them explore their universe. All telescopes can be equipped with a selection of instruments, including 35mm cameras, a photometer, CCD imagers, and a CCD spectrometer. The Advanced Camps feature access to professional instruments for imaging at visual and infrared wavelengths with large format CCD and NICMOS electronic cameras, respectively. A complement of computers allows Campers to analyze data using professional languages and to simulate astronomical phenomena.

During the daytime, internationally known scientists speak on current scientific topics, including the latest NASA space missions. Students also explore the diverse geology and ecology of Mt. Lemmon though hiking and outdoor demonstrations. Space artists illustrate how science becomes art. All Camps include an in-depth tour of the University of Arizona’s Mirror Laboratory, now producing the world’s largest telescope mirrors.

For more information on Astronomy Camp, visit the Camp’s internet headquarters at or contact the authors via email.

For More Information

• To learn more about "one-time use" cameras, visit Kodak’s website at or Fujifilm’s at

• For instructions on building a camera mount for your astrocamera, the following are good sources:

Dennis di Cicco, "A Simple Camera Mounting for Astrophotography," Sky & Telescope, October 1985, p. 391.

G. Haig, "A Simple Camera Mounting for Short Exposures," Sky & Telescope, April 1975, p. 263.

John Iovine, "Build an Astrophoto Platform," Astronomy, November 1992, p. 60.

• To determine the times and brightnesses of "Iridium flashes" and those of other artificial satellites, simply go to this fascinating website:

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