Milestones:Commonwealth Solar Observatory, 1924

Title

IEEE Special Citation: Commonwealth Solar - Mount Stromlo Observatory, 1924

Citation

Since 1924, the Commonwealth Solar Observatory has preserved the history of solar observation, optical munitions manufacturing, optical stellar research, and world-class development of astrophysics instrumentation in Australia. The Observatory has also become a major partner in developing the Australian space industry, including the design and supply of components for the world’s largest optical telescopes, while simultaneously furthering public education.

Street address(es) and GPS coordinates of the Milestone Plaque Sites

Cotter Road, Weston Creek, ACT 2611, 35.32087 S, 149.0007 E., Cotter Road, Weston Creek, ACT 2611, 35.32087 S, 149.0007 E.

Details of the physical location of the plaque

Entrance Hall of Visitor Centre

How the intended plaque site is protected/secured

Its inside the Visitor Centre that is closed when not in use

Historical significance of the work

IEEE Special Citation in History is requested for 100 years of continued service to the community. History The Commonwealth Solar Observatory (CSO) is one of the oldest astronomical institutions in Australia and the Southern Hemisphere. The Oddie Telescope Trial [24]: There was early interest among the astronomy fraternity in Melbourne in establishing a solar observatory in Canberra. In February 1910 the Commonwealth government invited Pietro Baracchi, the Victorian Government Astronomer, and a party of four to the Canberra area to select a suitable site for an astronomical observatory [4]. With a telescope donated by James Oddie, Baracchi established a small observatory on Mount Stromlo in May 1911. Within months of the proclamation of the Federal Capital Territory, astronomers from Melbourne had installed the 9-inch Oddie Refractor on the summit of Stromlo in order to site-test the mountain. Baracchi regularly visited the site until 1913 when he reported that it 'fulfilled the most essential requirements for any class of delicate astronomical work'. The Oddie Dome was among the first Federal buildings to be constructed in the ACT. It was designed and constructed by the Department of Home Affairs. Astronomers later used the telescope to take spectra of southern stars, gathering information on their age, size and chemical composition; measure the orbits of binary stars; and search for remnants of supernovae in the Milky Way [5].

The Solar Observatory: Despite lobbying since around 1905, after World War 1 the campaign to create a national observatory was taken up again. Astronomer Walter Geoffrey Duffield was the main driving force in efforts to fill the latitude gap between the USA and India that would allow the Sun to be kept under constant observation. The Commonwealth Government gave final approval in 1923, and Duffield was appointed as the foundation Director of the new Commonwealth Solar Observatory in January 1924. The building was designed to become the focal point, the administrative centre and the social heart of the Observatory. The building included two octagonal towers. The one at the eastern end was to carry the heliostat or sun telescope and one at the western end was for a conventional telescope (occupied by the Farnham telescope). The main building was constructed between 1924 and 1926. Work on the solar laboratories, including a long tunnel to house a spectrograph, took another 2 years to complete due to the blasting needed to excavate the basement and tunnel. During this period the Observatory was based in a wing of the Hotel Canberra (now the Hyatt). The Heliostat was the main instrument of the Commonwealth Solar Observatory from 1931 to 1946. It was housed in a small dome above a vertical tower, which led to the solar laboratory in the basement. The Heliostat [25] used two flat mirrors inside the dome to track the Sun and pass its light down the tower through a 12 inch lens. At the bottom of the tower, the light beam was reflected by another flat mirror to focus in one of the measuring instruments. The main instrument was a 3-prism spectrograph, regarded as one of the best in the world. This instrument was used to produce the Atlas of the Solar Spectrum which became the prime reference in the field of solar research for many years. Research was also carried out on the interaction between solar flares, sunspots and their effects on the Earth, particularly the upper atmosphere.

Wartime Precision Manufacturing: The Second World War dramatically changed the role of the observatory. The Commonwealth Solar Observatory operated as an Optical Munitions Factory, designing and manufacturing gun-sights and other equipment to aid the war effort. The Observatory swelled in size with a number of new workshops being constructed, and the staff numbers grew from 10 to 70. Mount Stromlo was the only Optical Munitions Factory in Australia equipped with the expertise and facilities to both design and manufacture munitions. Many of the new engineers were German Jews, released from a prisoner-of-war camp under the care of Director Richard Woolley. The Observatory also acquired responsibility for the Commonwealth Time Service in 1944 and this responsibility remained until 1968.

Transition to Stellar Astronomy: While the main focus of the observatory in the early years was on the study of the sun, parallel work was undertaken on observation of the stars. The 6 inch Farnham Telescope7 was installed in 1928 in the dome on the west wing of the building. Because of its small size, the Farnham had only limited use, but some of the earliest spectroscopic classification of southern stars was done with it and in the 1940s it was used to investigate variable stars. A 30 inch Reynolds Reflector telescope was donated to the observatory in 1924 and was erected between 1927 and 1929 in a separate dome near the Solar Observatory building. Itwas the first reflecting telescope at Mt Stromlo and until the 1950s it was the largest operational telescope in the southern hemisphere. During the 1940s the Reynolds reflector was used for some of the first detailed surveys of southern stellar types, and in the 1950s to study stars in the Magellanic Cloud galaxies8 [20-22]. After the Second World War the research efforts of the Observatory changed from solar tostellar astronomy and the Heliostat gradually fell into disuse.

Since its inception in 1911 this facility has evolved and is engaged in many fields such as: astronomy, engineering, physics, computer science, technical communication and education even today. There are very few facilities in the world that have evolved over the time like the CSO but still operating as world class leader in such diverse fields.

Features that set this work apart from similar achievements

The first notable research achievement was with the Heliostat and spectrograph were used by Clabon Allen in the 1930s to produce an Atlas of the Solar Spectrum. By analysing the intensity of the dark lines that cross the Sun's spectrum, Allen made a significant contribution to the understanding of the elements that make up the Sun' atmosphere and developed a Solar Atlas which gained the Observatory international recognition and became an important reference to solar researchers for many years.

In the 1950s astronomer Ben Gascoigne used the Reynolds telescope to study stars in the Magellanic Cloud galaxies, leading to the discovery that the universe was twice the size and age than previously thought. This work was supported by Gerald Kron, a US engineer turned astronomer who was expert in constructing instruments for astronomical purposes, especially photoelectric photometric instruments [20-22]

In 1957, Stromlo research engineer Kurt Gottlieb captured the first Western photograph of the Soviet Union’s Sputnik 1, the first artificial satellite. The image graced the cover of the New York Times.

In 1984 Stromlo scientists Mike Bessell and John Norris discover the oldest star, a record which stood for over 20 years. The same team reclaimed this title in 2014. Stromlo astronomer Ken Freeman was one of the first people to suggest the presence of an invisible mass in the Universe. In 1970 he ‘weighed’ some spiral galaxies by calculating the mass of all the visible objects, revealing that there was not enough visible mass to create enough gravity to hold the galaxy together. The missing mass was called ‘dark matter’, which we now know makes up about 25% of the Universe. In 1992 Mt Stromlo embarked on the MACHO project (Massive Astronomical Compact Halo Objects), in an attempt to identify the source of the mysterious 'dark matter'. The project ruled out MACHOs as an adequate explanation, and also led to the first discoveries of exoplanets (planets beyond our own solar system).

From 1994, Mount Stromlo Director Jeremy Mould led the team that used the Hubble Space Telescope to accurately determine the Hubble Constant (the rate of the Universe’s expansion). From this finding, the age of the Universe was recalculated to be about 13 billion years old.

In 1998, following observations of supernovae using the Reynolds Reflector, Mt Stromlo researcher Brian Schmidt (along with two other astronomers from the United States) published evidence that the Universe is expanding at an accelerating rate. This observation led to the team’s discovery of ‘dark energy’, which accounts for about 70% of the Universe. Professor Schmidt was named a joint winner of the 2011 Nobel physics prize for his ground-breaking research on supernovae and the expansion of the universe.

The site is significant nationally as it helped define not only time but the layout of the national capital, and in 1914 provided the data to show the suitability of Mt Stromlo as the location of the Commonwealth Solar Observatory and later the Mt Stromlo Observatory joining the Australian National University and producing amound the very first PhD graduate in what has until then been an research oriented university, and is now a leading teaching and research university.

Significant references

The Engineering Heritage Recognition Program https://portal.engineersaustralia.org.au/system/files/engineering-heritage-australia/nomination-title/HRP.Mount%20Stromlo.Nomination.V7.%20Jan%202018.pdf One Stop Shop: One of the most unique aspects of the Mt Stromlo Observatory was its capacity as a fully integrated workplace. While the main purpose of work on site was astronomy, all supporting infrastructure was on site to enable the research, development, design and manufacture of all the required instrumentation, optics and electronics. While it is common for the astronomers themselves to be acclaimed for their work, it must not be forgotten that the engineers, technicians, mechanics and assistants in the workshops were the key driving force behind the technology and developments which enabled many of the most famous astronomical discoveries. ...The Engineering and Technical staff worked closely with the astronomers and researchers - innovating and creating instrumentation to enhance the observing capacity of the existing telescopes. They were also involved in the development of exceptionally complex projects and commissions, building whole instruments from the ground up. ...The workshop complex ... was completely destroyed in the 2003 firestorm. After taking up temporary lodgings on the ANU Acton Campus - the workshops were replaced by the new Advanced Instrumentation and Technology Centre https://www.anu.edu.au/news/all-news/new-laser-to-help-clear-the-sky-of-space-debris Laser Ranging and space debris tracking: A Satellite Laser Ranging (SLR) Observatory was installed on Mt Stromlo in 1998 adjacent to the Observatory. It was built and operated by Electro Optic Systems Pty Ltd for Geoscience Australia, in collaboration with the Mount Stromlo Observatory. The initial facility was destroyed by fire in 2003, but the redevelopment that was already in progress enabled a new facility to be opened in 2004. The shared research centre incorporates a number of functions including the tracking of space debris to avoid collision with satellites, the Geoscience Australia laser ranging facility, a telescope test facility and an atmospheric monitoring facility. Laser ranging is used by Geoscience Australia as part of a world-wide network of stations to determine the precise orbit of reference satellites and thereby to monitor changes in the position of the stations on the Earth’s surface.

References: 1. https://portal.engineersaustralia.org.au/heritage/mount-stromlo-observatory-1924 2. https://portal.engineersaustralia.org.au/system/files/engineering-heritage-australia/nomination-title/HRP.Mount%20Stromlo.Nomination.V7.%20Jan%202018.pdf 3. Australian Heritage Database, Mount Stromlo Observatory Precinct, Mt Stromlo Rd, Mt Stromlo, ACT, Australia, Commonwealth Heritage List, Place 105309, 22/06/2004 4. Mount Stromlo observatory conservation management plan, Tanner Architects, 2004 5. The Mount Stromlo Observatory Precinct Heritage Management Plan, GML Heritage, July 2015 6. Mt Stromlo Heritage Trail, ANU 2014 7. http://msoheritagetrail.anu.edu.au/ 8. http://msoheritagetrail.anu.edu.au/timeline 9. http://msoheritagetrail.anu.edu.au/telescopes 10. ScienceWise - Autumn 2011, Taming the jitters: Developing the adaptive optics for the world’s most powerful telescope, http://sciencewise.anu.edu.au/articles/jitters 11. ANU RSAA Instrumentation http://rsaa.anu.edu.au/research/themes/instrumentation 12. ANU Heritage Office Oral History Recordings, Interview with Hermann Wehner, 18 Feb 2014 13. https://openresearch-repository.anu.edu.au/handle/1885/117119 14. Interview with Gabe Bloxman: optics specialist, and John Hart: engineer, 12 March 2014 15. https://openresearch-repository.anu.edu.au/handle/1885/117112 16. Stromlo; an Australian observatory, Tom Frame and Don Faulkner, Allen & Unwin, 2003 17. Mount Stromlo Observatory; from bush observatory to the Nobel Prize, Ragbir Bhathal, Ralph Sutherland and Harvey Butcher, CSIRO Publishing, 2013 18. ANU Mount Stromlo 2004 site interpretation brochure, formerly accessed at http://www.mso.anu.edu.au/info/documents/MSOSignage2004.pdf and referred to in A Century of Canberra Engineering, Keith Baker, Engineers Australia 2013, p79 19. https://www.mso.anu.edu.au/gallery3/index.php/first100years/album17 20. https://articles.adsabs.harvard.edu/pdf/1953ApJ...118..502K 21. https://articles.adsabs.harvard.edu/pdf/1957AJ.....62..205K 22. https://articles.adsabs.harvard.edu/pdf/1966MNRAS.134...59G 23. History of Astronomy in Australia: Big-Impact Astronomy from World War II until the Lunar Landing (1945-1969) https://arxiv.org/pdf/2104.00901.pdf 24. https://www.youtube.com/watch?v=fHF3tiS3Ths 25. https://rsaa.anu.edu.au/observatories/mount-stromlo-observatory/telescopes

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