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Home > News > Historic Lowell Observatory -- Still Going Strong After All These Years
This is the 24-Inch Alvan Clark Refractor at the Lowell Observatory in Flagstaff, Arizona -- the most historically significant telescope at the observatory. This refracting telescope was purchased by Percival Lowell in 1896. It was built by the skilled telescope maker Alvan Clark in Boston, then hauled to Flagstaff by train. Around the turn of the century, Percival Lowell used this telescope to study Mars and what he believed to be the canals that were constructed by intelligent beings on the planet. During the 1960s, this telescope was used for a Moon mapping project sponsored by the Air Force to obtain the first good views of where Apollo astronauts would make their historic landings on the Moon. (Image Credit: Tom Alexander/Lowell Observatory)
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A unique telescope housed in a 1920s stone building on Lowell Observatory’s Mars Hill continues to serve as astronomer Wes Lockwood’s main telescope in a project originally started a half century ago to monitor solar irradiance variability.
After the arrival of astronomer Harold L. Johnson in the early 1950s, the telescope was used to study the Sun’s light reflected from the planets Uranus and Neptune. Over half a century later, The Lowell Observatory 21-inch, equitorially mounted Cassegrain Reflector continues its productive work in monitoring the brightness of Uranus and Neptune against a reference set of precisely measured sunlike comparison stars -- a program in its 52nd year.
“We never expected this work would go on for a half a century,” said Wes Lockwood, Lowell Observatory Astronomer. “But, once we realized we had a unique product whose value increases the longer it goes on, it seemed crazy to quit.”
The telescope was installed in 1953 in a stone building with a fully retractable roof. Although no solar variations were ever detected in this original quest of monitoring the Sun’s light – and indeed could not have been detected given the Sun’s now well-known, miniscule 0.1 percent variation over the solar cycle – this 21-inch telescope has made it possible to measure the tiny fluctuations of stars that closely resemble the Sun.
The 21-inch was first used for Johnson’s seminal work defining standards for the UBV (Ultraviolet, Blue, Visual) photometric system and measurements of color-magnitude diagrams for nearby open clusters. Since then, the Lowell Observatory 21-inch has supported a steady stream of variable star work, early interstellar polarization measurements, drift scans of the Andromeda Galaxy, characterization of the variability of sunlike stars, 50-plus-year lightcurves of Uranus and Neptune, and a complete 29.5-year seasonal lightcurve of Saturn’s moon, Titan.
Other active telescopes at the Lowell Observatory include the 72 inch Perkins equatorially mounted Cassegrain Reflector, the 42 inch Hall fork mounted Ritchey-Cretien, and the 21 inch AstroMechanics fork mounted Cassegrain Reflector.
With fully robotic photometric telescopes now taking over much of the stellar research begun with Lowell’s 21-inch telescope, the future of this historic workhorse is in question. Nevertheless, it continues to fill a niche not easily satisfied by more sophisticated, modern instrumentation.
In 2007, Uranus, on its 84-year long trip around the Sun, will reach equinox as the Sun crosses its equator from South to North. Sunlight is now illuminating northern latitudes for the first time in decades. In collaboration with colleagues using the 10-meter Keck telescope on Hawaii, astronomers at the Lowell Observatory will assemble a decades-long seasonal picture of how Uranus varies in brightness and how its clouds and zonal features change from year to year.
For More Information:
http://www.lowell.edu/press_room/releases/recent_releases/21_in_results.html
http://www.lowell.edu/online_newsletter/fall_04/2713_nights.html
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