We said farewell to Barry Adcock and welcomed Perry Vlahos as our new President who, in a short presidential address, confirmed the continuation of ongoing projects and encouraged all members to an active participation.
Introducing the syllabus item, Jim Pollock outlined plans for the acquisition of all the left-over parts of, and the eventual restoration of the Great Melbourne Telescope (GMT). It will be a major undertaking, extending over many years and requiring massive funding. But in the light of the telescope’s colourful history the project is sure to become a significant part in Australia’s Cultural Heritage. Barry Clark then
presented his topic, “What went wrong with the Great Melbourne Telescope”.
Much has been said and written about the Great (Southern) Melbourne Telescope: its painful birth, its
troubled life as the “Great Southern Telescope”, its inglorious retirement followed by an eventful awakening to its full potential at the Mt Stromlo Observatory and finally its sad and fiery demise in the Canberra bush fires on 18 January 2003. The telescope – a Cassegrain as recommended by the Royal Society of England – was constructed in 1868 in Ireland by Hershcell for the Melbourne Observatory. The Great Melbourne Telescope (as it
soon became known) was from 1868 until 1908 the largest steerable, reflecting telescope in the world.
Following its mediocre existence in Melbourne – de-commissioned as scrap in 1944 – the telescope was acquired for the Mount Stromlo Observatory and transferred to the site in 1955. To accommodate the telescope a new dome was constructed and upgrades were carried out with new technology in 1976, in the 1980s and completed in the 1990s to transform the telescope into an exceptional research tool. Adapted to search for dark matter in the MACHO project (the search for the Universe’s enigmatic ‘missing mass’) it was the first instrument to document gravitational lens light
refraction. It measured luminosity of 6,000,000 stars every night and searched for trans Neptunian objects. In the 1990s the telescope became the single most important research telescope on Mount Stromlo, providing the RSAA with world wide acclaim.
So, what went wrong in Melbourne? Barry showed the long list of claimed “faults” attributed to the telescope at the time, such as: use of speculum instead of silvered glass for the mirror; long focal length; tube vibration in the open air; friction and/or slack in the support system, local tampering; staff shortcomings; overly adherence to the Royal Society’s tasking; incapability of colonials to re-polish the mirror, and so on.
In hindsight it seems obvious now that the so-called failures of the telescope in
Melbourne were in the main due to inadequate funding and to management priorities. Robert Ellery, Government Astronomer directing the use of the telescope was, in 1868, unfamiliar with reflecting telescopes and may have thought the GMT an unwelcome distraction of resources. Without motivating challenges and staffing kept at subsistence level the telescope was in time looked at merely as a viewing platform for the public. Yet, Barry reiterates, there was nothing radically wrong with the
telescope. So, why does everyone think is was a failure? Because a great authority once said so in a report (Ritchey 1905) – failure of the Melbourne reflector has been the one of the greatest calamities in the history of instrumental astronomy – and this statement has been repeated over and over since then, out of context.
There was no great fault with the GMT, Barry concluded. At the time Ritchey wrote his report the GMT was capable of excellent performance, apart from some loss of light by tarnish. The only major problem was inadequate resourcing for operations and reporting. Dozens of textbooks have got it seriously wrong ever since. AK