Indiana University
Goethe Link Observatory
Longitude: 86.42.0 West --- Latitude: 39.53.0 North
Construction of the Goethe Link Observatory started early in 1937 and was operational in early 1939. It contains a 36-inch folded Cassegrain reflector. The primary mirror was a test blank that had been poured as experimental in development for the 200 inch mirror for the Mt. Palomar Telescope. The visual tests showed the surface of the glass was ranked as one of the most accurately figured mirrors ever made at that time.
The original telescope was a Newtonian, but in 1966 an entirely new telescope tube with f/10 Cassegrain optics was installed. The original f/5 primary mirror was retained, but its ribbed construction prevented cutting the central hole needed for a normal Cassegrain focus. Instead, a tertiary flat was inserted to reflect the converging beam of light from the secondary and direct it toward any of three observing ports at the circumference of the tube.
The telescope weighs 5,000 pounds. The concrete pier extends down to solid bed rock and weighs 200 tons and extends 30 feet above ground level.
The dome is 34 feet in diameter with an opening 8 feet wide and weighs 34 tons. The opening extends 4 feet past the zenith. The shutters weigh one ton each.
The building is made of Oak posts and knotty-pine paneling and does not touch the pier thus keeping any vibrations from transfering to the pier and the telescope.
On the first floor there is an auditorium, darkroom, living quarters, and a library. Just below the observing deck there is a 250-square foot control room with inclined glass windows that look into the dome.
The Indiana Astronomical Society wishes to thank the Indiana University for giving us permission to access and use the Link Observatory to help promote Astronomy.
©2005 Indiana Astronomical Society