Telescope relies on tape encoders

Based in Arizona, the Discovery Channel Telescope sits almost 8,000’ above sea level and is currently the fifth largest device of its type in the United States. The installation uses Heidenhain ERA 880 tape encoders as part of the system to accurately control its axes of movement. When focusing its 4.3-metre aperture, Heidenhain says that its accuracy has been measured at 0.19 arc seconds on the azimuth, 0.38 arc seconds on the Cassegrain, and elevation at 0.03 for 90° motion—all exceeding the original specifications issued for the project