Virtual Tour | McDonald Observatory

Virtual Tour of McDonald Observatory

82" telescope
82 inch Otto Struve Telescope

On behalf of the University of Texas at Austin, welcome to McDonald Observatory and the summit of Mt. Locke. The dome in front of us houses the 82 inch Otto Struve Telescope, the first telescope to be built at the Observatory. When dedicated in 1939, it was the second largest telescope in the world. It has been in constant use ever since.

For a unique perspective on the 82 inch Telescope, follow this link to a

360º panoramic movie (approx. 930k)

For slower connections, try this smaller, lower resolution movie (approx. 234k)

We use the historic 82 inch Otto Struve Telescope for Special Viewing Nights...the best telescopic views around!

William Johnson McDonald, circa 1920

The 82 inch telescope was made possible by the bequest of William Johnson McDonald, a Paris, Texas banker. He passed away in 1926 and left the bulk of his estate, some $1 million dollars, to the University of Texas to build a large telescope.

At the time, the University had little in the way of an academic program in astronomy, so Texas joined with the University of Chicago in a partnership to found McDonald Observatory. It was a joint venture for thirty years but has been under the sole purview of the University of Texas since 1962. Today, the University is home to one of the best education and research programs in astronomy worldwide.

McDonald is also responsible for his observatory being one of the most publicly accessible astronomical research centers in the world. When he bequeathed his estate to The University of Texas in 1926, he did so "...for the purpose of aiding in erecting and equipping an astronomical observatory to be kept and used with and as a part of the University for the study and promotion of astronomical science." As early as 1934, astronomers at McDonald Observatory were conducting public programs using a 12-inch telescope.

Today, the Frank N. Bash Visitors Center conducts a variety of Public Programs at McDonald Observatory.

United States At Night

It isn't just the big telescopes that attract so much attention to McDonald Observatory, it is also the quality of the observing site. There are four conditions that make this such a good location for astronomy:

McDonald Observatory is located so far south (30 degrees north of the equator), that many celestial objects are visible above the southern horizon from here that remain forever below the horizon to observatories located farther north.
At an elevation of nearly 7,000 feet above sea level, McDonald Observatory is above a substantial portion of the moisture in the Earth's atmosphere. This helps keep the sky steady and transparent.
The climate in the Davis Mountains is dry. The annual rainfall is 13 inches. On average, two out of three nights are clear.
McDonald Observatory is located in "the middle of nowhere". The nearest major city is 160 miles away so the Observatory enjoys some of the darkest night skies in North America.
Check here for more information on Outdoor Light Pollution Reduction.

Hobby-Eberly Telescope

Looking to the north we see the Hobby*Eberly Telescope (HET) atop Mt. Fowlkes. When it was dedicated near the end of 1997, the HET became (and remains) the third largest single structure optical telescope in the world. Unique optical and mechanical designs allowed this instrument to be built at roughly 15% of the cost of other large telescopes.

Be sure to visit the HET Home Page.

McDonald Lunar Laser Ranging Station

Mt. Fowlkes is also the site of the McDonald Lunar Laser Ranging Station. A 30 inch telescope is used to fire a laser beam to retroreflectors left on the moon by the Apollo astronauts. By timing how long it takes the pulses of laser light to make the round trip from here to the moon and back (nearly 3 seconds), astronomers are able to measure the changing motions of the moon (and other earth orbiting satellites) to within one inch.

McDonald Laser Ranging Station Home Page
A more detail description of the Laser Ranging program. Several large (150k) pictures of the telescope in action.

Check out Laser Ranging's Rodent Control system. (33k)

107" telescope
107 inch Harlan J. Smith Telescope

The 107 inch Harlan Smith Telescope was the third largest in the world when dedicated in 1969 at a cost of $6 million. It was used by NASA to prepare to fly the Viking missions to Mars and the Voyager missions to the outer planets in our Solar System.

The moving parts of the telescope weigh 165 tons, yet it is so well balanced that it is moved by small electric motor. There are three different optical systems in this one telescope which make it an extremely versatile research instrument. Like the 82 inch Otto Struve Telescope, the 107-inch Harlan Smith Telescope remains in constant use every clear night of the year.

One night a month, typically on the Wednesday nearest the full moon, the 107 inch is opened for Special Viewing Night.

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