Good morning,
I received this news piece from another group I’m on, and thought it might
interest List members.
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The Great Melbourne Telescope
The Great Melbourne Telescope (GMT) is being restored after sitting
ingloriously out in the weather in Canberra for several years.
The Great Melbourne Telescope was built in Dublin in 1868 and erected at
Melbourne Observatory in 1869. At the time it was the second largest
telescope in the world and the largest in the southern hemisphere.
When Melbourne Observatory closed in 1944, the telescope was sold to the
Commonwealth Observatory at Mount Stromlo, Canberra. At Mount Stromlo the
telescope was given a new 50-inch glass mirror and became an integral part
of Mt Stromlo’s work from 1961 into the 1970s. In the 1990s the telescope
was rebuilt with two large-scale digital cameras for the search for evidence
of dark matter. Then in January 2003 a bushfire swept across Mt Stromlo, its
firestorm destroying the majority of the telescopes and buildings. Only the
large iron castings from the GMT, bent metal and broken glass remained.
Unloved and broken it sat in the extreme cold of Canberra’s weather for at
least four years until members of the Astronomical Society of Victoria (ASV)
embarked on a mission to rescue it in 2008. Lacking plans or drawings and
missing at least 180 parts, a team of ASV volunteers has been painstakingly
dismantling it in a large restoration area in Melbourne. Every available
working part has been identified, numbered, restored or rebuilt.
The GMT was built with a speculum mirror lens and is the last of the great
mirrored telescopes. An unforgettable moment for the restoration team came
in 2010 when a staff member found a box in the museum’s store and called for
expert help to confirm the contents. The box contained the original
flotation system for the telescope’s one-ton white bronze mirror. It was a
joyous day for the GMT reconstruction team who had long wondered what had
happened to this item of 19th century engineering which provides a balanced
bed of 48 steel balls to support the back surface of the mirror evenly,
keeping distortion of the mirror surface to less than a 1/10,000th
millimetre.
The dollar value of the ASV work is incalculable, unlike the restoration
costs. Funding for the project is an ongoing challenge. The replacement
mirror alone, is likely to be in excess of $200,000. Many parts of the GMT
can be repaired or remade in the restoration area by the combined efforts of
Museum Victoria staff and the ASV volunteers. When larger equipment is
required, it is manufactured by the staff at Scienceworks.
A 2-metre high photograph of the telescope from 1885 is a key reference for
the group as they establish which parts are original and which were replaced
at Mt Stromlo Observatory. The ASV team hope to have the GMT back home at
Observatory House in 2019 to coincide with the 150th anniversary of its
arrival in Melbourne. Everyone interested in following the progress of the
GMT restoration or wanting to donate to this great cause can do so through
www.greatmelbournetelescope.org.au
Written from information at www.greatmelbournetelescope.org.au and an
article written by Liz Clarkson (also on the GMT website).
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Cheers, John
John Pickard
[email protected]
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