The Heinrich Hertz Telescope and the submillimeter telescope observatory

The Heinrich Hertz Telescope (HHT), with the associated instrumentation, and the Gene Frazier Enclosure form a facility dedicated to submillimeter-wavelength radio astronomy that is operated by the Submillimeter Telescope Observatory (SMTO). It is located at 3200 m altitude on Mount Graham in eastern Arizona. The reflector has a diameter of 10 m and an accuracy of 12 mu m rms. It is composed of 60 panels, made of aluminum honeycomb with carbon fiber reinforced plastic (CFRP) skins. The absolute pointing accuracy is about 2 ", with a tracking accuracy of better than 1 ". The corotating enclosure is opened during observations. The reflector support structure is made of low-expansion material (CFRP and invar steel). This allows the use of the telescope during daytime, under differential warming by the Sun, without a measurable decrease in its efficiency or pointing stability. We describe the salient features of the site and the enclosure, the structural design, the holographic measurement of the reflector surface, and the optics layout of the telescope. We also present some results of the pointing and efficiency calibration. Finally, a few examples of early astronomical results illustrate the potential of the telescope for high-quality submillimeter-wavelength astronomy.