THE LEGACY OF THE 31" by Dawn JenkinsAstronomy from Northern Ohio can be frustrating. We suffer the phenomena of "lake-effect" which creates clouds that blow our way. We are the home of the Mid-Western High which takes our name because no other place on Earth but the American Midwest can a high pressure system be accompanied by rain. Neither our high northern latitude nor the increasing city lights have dampened our enthusiasm for observing, the astronomical spirit lives on here. It was with this spirit that Norman Oberle suggested that area amateurs should have the benefit of a large aperture (25 inches or larger) telescope with sufficient focal length for excellent visual work. In 1968 Norm formed the Lake Erie Astronomical Project (LEAP), which included Jim Thomas and other area amateurs. Norm approached General Electric and was given a 44" blank which weighed 700 pounds. Later, he was given a better 31" blank of fused quartz that was intended for the McMath solar observatory at Kitt Peak as an optical flat, but was later rejected for a larger glass. It was a bit lighter, weighing only 235 pounds. Norm purchased a farm in Wellington and work began from a garage/workshop on that site. Norm Oberle and Jim Thomas spent 2,000 hours grinding and polishing to work the mirror into an oblate spheroid. Work was suspended, but resumed in 1973 from Norm's house. Norm worked with Jim Thomas in a basement workshop. The final correcting was done by hand with 16" and 10" sub-tools. During the Thanksgiving vacation in 1973, the mirror was tested at North Royalton High School. The mirror was found to be parabolic within 1/12 wave. It's focal length is 213.62", or f/7. Later, Norm drove the mirror to Brackenridge, Pennsylvania where it was coated by Liberty Mirrors free of charge. Norm and Jim Thomas built a temporary altazimuth mount. It was 1974, before the introduction of the Dobsonian-type of instrument when all large telescopes were equatorially mounted. The altazimuth mount was less massive because the mass is over the center of gravity. Using this system to observe, astronomers had to climb a fifteen-foot ladder to the eyepiece and an equatorial mounting would have increased the climb even more. In Norm's yard they poured one cubic yard of concrete for the telescope mount, in his garage they constructed the mirror cell with power tools. The tube was cardboard which was hand painted with fiberglass. It took seven layers of fiberglass and was 18 feet long. They rolled the tube out into the yard on rollers and used an engine-lift bring it upright. They had to jack up the mirror to get it into the cell. Then, to balance the system, forty pounds of weight was added to the front of the tube.
The 31" was used in the temporary mount until 1977 when the fiberglass on the tube cracked, allowing moisture into the card board center. Once the sagging became intolerable, the instrument was tucked away in Norm's garage until two Ohio Astronomers, Bruce Scodova and Doug Wereb invited Norm Oberle to a Richland Astronomical Society meeting in 1981. Today Bruce Scodova works for Allen Bradley in Cleveland and Doug Wereb is a professional astronomer at the University of Virginia. The Richland club is situated in the Hidden Hollow camp ground, and has long held meetings in the clubhouse on the grounds. In September 1982, LEAP offered the 31" mirror for the Hidden Hollow site if RAS could provide a building for it. RAS members worked very hard to secure donations for the project. In the end, a large portion of the financing came through a RAS club member, Warren Rupp, who's name has been given to the observatory. The Dobbins Instrument Company in Lyndhurst, Ohio was selected to build the observatory. Tom Dobbins contacted Gary Kader, an amateur astronomer and engineer, to work on the building which Gary modeled after classic Warner and Swasey designs. Tom Dobbins contracted All-Custom Fabricators and Erectors to make the tube. The open tube helps to equalize the mirror more rapidly than a solid one. Mr. Dobbins also arranged for the Lift-A-Lot, a scissors-type lift that hefts the observers up to the eyepiece. The site preparation was done by Bernie Dillon of Friendly House. It included cutting trees, grading and construction of a parking lot. This time many pounds of concrete were used to create pillars for a cross axis mount, and the tube was erected by crane. The building was finished in fall of 1985. The complete telescope and mount weigh over 7,500 pounds, and sit under a thirty-foot Ash Dome. The instrument is operated by Richland club members. The views through the big 31" are alternately described as fantastic and incredible. I looked through the eyepiece for the first time on May 29, 1987 on a lousy night during our OTAA convention. M-13 was impressing everybody! I was amazed to see the disk of Uranus so plainly. (I mean it was huge!) I realized that this instrument would be an adequate tool for observing and studying clusters of galaxies! Norm Oberle can describe spectacular sights he observed with this instrument in the privacy of his own front yard during the three years it was mounted there. Once a curiosity, the 31-inch has become a valuable tool for area amateurs. The Richland Astronomical Society is open to requests for time from amateurs interested in scientific work or purely observational astronomy. Today, the Richland Astronomical Society runs the 31-inch during public programs and late night observing from the remote site. The OTAA is also working to promote the telescope at the Warren Rupp observatory. What the Board wants to see is the real support of interested area amateurs. The road was long and the climb was high, but Norm Oberle's dream is now a reality. This article was written on October 27, 1987 and was published in The
Asteroid Belt. |
