TSU obtained an 81-inch, f/1.5 primary mirror for its telescope on the surplus market. This saved the project a considerable amount of time and money. The mirror was made for an Air Force telescope in about 1970 and had most recently been part of a zenith-looking lidar system in Japan. The original instrument had been an alt-azimuth camera that could swing through 180 degrees from zenith to nadir. The mirror came with an aluminum cell, weighing about 2500 pounds, and a system of pucks for supporting it in an alt-azimuth mount. We decided to build an alt-azimuth telescope to take advantage of this existing scheme for supporting the primary mirror, to simplify the structural design of the rest of the telescope, most notably the secondary-mirror supports, and to keep open the option of using the existing mirror cell.

Originally, the telescope was to be constructed entirely of structural steel because it is the cheapest, most conventional material to use, with a moderate coeffficient of thermal expansion. Furthermore, some critical parts of the telescope would almost certainly have to be made of hardened steel. However, building a steel mount would have scrapped the existing intricate mirror cell, since the differential thermal expansion between aluminum cell and a steel fork would have been of the order of 0.04 inches over the operating temperature of the telescope. Although we could have designed a sliding altitude bearing to accomodate this much differential expansion, the lateral support of the telescope tube by only one tine of the fork would have been undesirable.

We are building a telescope designed solely for fiber-fed spectroscopy, both to simplify the design and to protect against the tendency to lard on more operations-complicating instruments. The instrument head in the telescope, then, could be made very small, no bigger than the photometer in one of our Automatic Photometric Teleseopes. It could therefore be any place in the telescope, and we chose to put it between the two mirrors of a Cassegrain system. We chose a Cassegrain system to give a conveniently located focus with reimaging of the f/1.5 prime focus to f/8. An alternative would be reimaging at the prime focus with a Barlow lenses, which would put the guide camera and fibers up at the top of the telescope with much longer, more complicated runs to their controls and to the spectrograph.

The telescope project is being carried out by a small group of research faculty at Tennessee State University, primarily Joel A. Eaton, who serves as project manager and chief engineer, and Michael R. Busby, who serves as financial officer and political troubleshooter. They are assisted from time to time by Frank Fekel, an expert in high-dispersion spectroscopy, and Greg Henry, who has wide experience in maintaining astronomical instrumentation. The late Darrell Hinton contributed advice about engineering in the earlier stages of the project. We are therefore using numerous consultants and temporary technical workers, about whom we have a separate page. An organizational chart shows this management structure.