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Earth Notes

Earth Notes - Seeing Astronomically

General Dynamics, Inc.
This photo shows a panoramic view of the interior of the Discovery Channel Telescope facility observing level. The mount is situated on a platform to allow for proper telescope positioning and pointing during active operations.

Flagstaff, AZ – In 1894 Percival Lowell established an astronomical observatory on a northern Arizona mesa just outside the tiny town of Flagstaff. Why? He'd searched around the world for an appropriate place for a major telescope. When he settled down, it was in part because of good viewing conditions but also because he found suitable land close to a town with amenities and good transportation.

Astronomers still balance these factors to determine where to place their observatories. The most important is what astronomers call good "seeing." That refers to how much or little an object twinkles, or appears fuzzy, when viewed through a telescope.

Astronomers want steady, focused objects. Poor seeing results from an unstable atmosphere. Hot air rising from the ground, turbulent winds, and storm fronts can cause poor seeing. Forested areas, higher altitudes, and steady winds tend to make for better seeing. So does a dark sky not too altered by human lighting.

Long after Lowell's day, engineers found that astronomical seeing was excellent at Happy Jack, a site 45 miles southeast of Flagstaff. In 2005, Lowell Observatory broke ground there to build the new Discovery Channel Telescope, or DCT.

DCT will be Lowell's flagship telescope working on a variety of research projects. It's located on Forest Service land right off a county highway. That adds the convenience of easy access to the site. Surrounded by dark ponderosa pine forests and supportive, dark-sky-conscious communities, the DCT is gearing up for seeing clearly into space for a long time.

-Cecile LeBlanc