Friday, 25 April 2008

Siding Spring

On a clear day, the observatory dome gleams in the sunshine. But this wasn't a clear day. It was rainy, foggy and bloody cold. But the drive is splendid — it winds along the base of the Warrumbungles, past Timor Rock and then climbs into the hills.

Tourists can enter the Observatory to gawp at the telescope. On the way up the hill to the building, I met a couple from Kuala Lumpur who were visiting all the telescopes in the district. They had their work cut out for them. There's a shi … lot.

This is the Anglo Australian Telescope. You reach the observation deck via a lot of fire stairs or a claustrophobia-inducing lift. I took the stairs. That tested my aerobic fitness. Epic fail.

The dome enclosing the telescope is 50 m tall. I'm not sure of its radius because that was the one figure I didn't write down. The telescope itself is 15 m long with a primary mirror with a working diameter of 3.893 m.

That mirror was cast in Toledo, Ohio, from a synthetic glass-like material called Cervit, which is extremely stable and doesn't respond to temperature changes. From the U.S., it was shipped to Newcastle-upon-Tyne where it was figured — polished into shape — over three and a half years. It eventually arrived at Siding Spring in December 1973. After being coated with aluminium* to give a reflective surface, the mirror was fitted and the telescope inaugurated just under a year later.

I was impressed.

* It is recoated annually with just 2.5 g of Al.

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