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SpaceNut

Administrator

From: New Hampshire

Registered: 2004-07-22

Posts: 29,431

Re: A touch heaven from atop Palomar Mountain

Palomar Mountain is home to three optical telescopes, operated by the California Institute of Technology

Rising northeast of San Diego (33 degrees, 21 minutes, 22.82 seconds north by 116 degrees, 51 minutes, 56.34 seconds west, to be precise), Palomar is not the tallest mountain in the county, but for more than half a century, it has been one of the best places here or anywhere to gaze at the stars.

Quite spectacular what we can do with old telescopes as we add new features and hardware to them.

Hale Telescope 200-inch (5.1 meter) First light: 1949

Article has lots of interesting info..

Happy reading to Cindy and to all....

Palomar

Member

From: USA

Registered: 2002-05-30

Posts: 9,734

Re: A touch heaven from atop Palomar Mountain

*Yep.  What history.    Pyrex to the rescue!

Corning had never made anything like the proposed mirror, but the company succeeded on its second try. The resulting glass blank was huge: 17 feet in diameter, 4 feet thick and weighing more than 20 tons. A special train, moving less than 25 miles per hour, took 15 days to transport the blank to California for polishing.

At the same time, construction of the observatory had begun. It was an equally daunting task. Piers to support the completed telescope, which would weigh nearly 600 tons, were anchored 22 feet down into bedrock. The dome above rose 135 feet high with a 137-foot diameter, dimensions akin to the Pantheon in Greece. The shutters, which open to reveal the night sky, weigh 125 tons apiece.

Polishing the glass blank into a perfect paraboloid shape was painstaking, with workers hand polishing the glass using ever-finer solutions of grit. It was laborious. The process, interrupted by World War II, covered 11 years, from 1936 to 1947. In the end, almost 10,000 pounds of excess Pyrex was removed.

On Nov. 12, 1947, the mirror was transported from Pasadena to Palomar by truck, albeit very, very slowly. Three diesel tractors were needed to actually lug the mirror up the mountain. The 125-mile trip took 32 hours, an average speed of 3.9 miles per hour.

Two more years of polishing, aligning and adjusting were required before the mirror and the telescope saw first light. The telescope was named after Hale, who had died in 1938. Until 1993, it was the world's largest effective telescope.

Ever since, the Hale telescope has been used on almost every clear night. Initially, its ability to detect extraordinarily faint sources of light in the night sky was employed to measure the size of the universe and its rate of expansion. It was the first optical telescope to see a quasar and determine that these starlike objects were immensely far away.

Quasars – or quasi-stars – are small objects (perhaps no larger than our solar system) that produce more light in one second than an entire galaxy of stars.

Over the years, the Hale's original equipment has been updated, improved and replaced. New sensors, computers and other devices allow the telescope to detect light sources 100 times fainter than when it first went into service. In the course of a month, different kinds of cameras are attached to record different targets and phenomena, depending upon a researcher's interest.

These nights, the telescope is frequently used to study detail in regions of the universe where stars and planets are forming. It takes in-depth looks at the weather on Uranus and Neptune.

The Hale is also one of only a handful of telescopes using a laser, or adaptive optics.  A beam of light is shot into the night sky, creating an artificial star. The telescope then focuses on the laser point, correcting up to 2,000 times per second for any atmospheric disturbances. The result is a much sharper picture that has helped astronomers zero in on weather patterns on Titan, Saturn's largest moon, and see the shapes of asteroids.

How long will the telescope be used? At this point, there's no telling, said Scott Kardel, public affairs coordinator for the Palomar Observatory.  While bigger telescopes have stolen some of the Hale's thunder (and perhaps some of its potential funding), the scope remains much in demand by scientists.

"And that's not likely to change for a very long time," said Kardel.

The venerated Hale (deservedly so).    Always brings back memories of books and astronomy magazines of the 1970s-1980s, etc. (photos obtained via Hale published therein -- some of the best astrophotos of the time).

All the work which went into it.  Just the mirror-polishing process alone...

I've read this history before, years ago.

Thanks for posting that, SpaceNut.

--Cindy

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We all know [i]those[/i] Venusians: Doing their hair in shock waves, smoking electrical coronas, wearing Van Allen belts and resting their tiny elbows on a Geiger counter...

--John Sladek (The New Apocrypha)