Telescopes - Mount Stromlo Observatory

The Oddie Refractor

In 1909 a 9-inch refracting telescope, later named the Oddie Refractor, was presented to Prime Minister Alfred Deakin by James Oddie, a businessman and pioneer of the Ballarat region in Victoria. Peter Baracchi, Government Astronomer of Victoria, took receipt of the telescope and oversaw its installation at Mount Stromlo. Observations commenced in September 1911 and continued for two years. It was these observations that led to the selection of Mount Stromlo as the best location for the new Commonwealth Solar Observatory, which eventually opened in 1924.

The Oddie Dome was not only the first building on Mount Stromlo but was also the first Commonwealth building in Canberra. 

Astronomers used the Oddie Refractor 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.

From the 1970s, the Oddie Refractor was the main public outreach telescope at Stromlo and was used by thousands of amateur astronomers. 

In the 1990s, the Oddie was restored to its almost original condition and continued to be used for public outreach. 

The Oddie Refractor was destroyed in the 2003 bushfires but in 2011 it was faithfully recreated for the 100th anniversary of its arrival on site at Mount Stromlo. 

The Heliostat (Sun Telescope)

The Heliostat (Sun Telescope) was one of the earliest telescopes at Mount Stromlo Observatory. It was designed in collaboration with astronomers from overseas, particularly California’s Mount Wilson Observatory and Germany’s Potsdam Observatory, and built at Stromlo. It was constructed vertically in a shielded tower rather than horizontally, in order to produce higher quality images. 

Constructed lasted from 1926 to 1931, with delays experienced due to difficulties constructing the basement area of the telescope, with workers having to dig through solid rock to lay the foundations. The Heliostat made observations of the Sun by reflecting images through an electric mirror system in the turret and down the vertical tower into a 30cm objective lens located in an underground basement. In the basement was a 25cm mirror which directed the image onto a solar spectrograph.

In the 1930s, astronomer Clabon (Cla) Allen used the Heliostat to research the intensity of absorption lines in the Sun’s spectrum, which provided a greater understanding of conditions in the Sun’s atmosphere. It was also used to monitor the effect of solar flares and sunspots on the Earth.

From the 1940s, the Heliostat was seldom used, with work at Stromlo shifting from solar astronomy to stellar astronomy. The last significant work undertaken with it was in 1957 when the telescope was used to observe the transit of Mercury across the Sun. 

The Heliostat was destroyed in the 2003 bushfires, but a similar telescope is now located in the Stromlo Visitor’s Centre. 

The Reynolds Reflector

The Reynolds 30-inch Reflector, donated by British industrialist John Henry Reynolds, was the largest of the original telescopes at Mount Stromlo Observatory, built c. 1910 and installed between 1927 and 1930. 

It was the first reflector used at Stromlo. However, given the Observatory’s early focus on solar astronomy, it was infrequently used, with the Heliostat (Sun Telescope) being the preferred instrument. When the Observatory’s focus shifted to stellar astronomy after the Second World War, the Reynolds Telescope received much greater use and in the late 1940s a spectrograph was constructed so it could be used for spectroscopic observations, and in 1951 it was fitted with a new photoelectric photometer from Lick Observatory in California. Following these additions, the Reynolds Telescope became the Observatory’s primary research instrument. 

Ben Gascoigne used the Reynolds Telescope in the 1950s to observe variable stars in neighbouring galaxies and the Magellanic Clouds, which confirmed that the universe was twice the size and age than previously thought (ANU Research School of Astronomy and Astrophysics, n.d.).

In the 1990s, the Reynolds Reflector was used to monitor supernovae and contributed to Brian Schmidt’s Nobel Prize winning discovery of an accelerating universe (ANU Research School of Astronomy and Astrophysics, n.d.).

The Reynolds Reflector was destroyed in the 2003 bushfires, although the dome remained and was refurbished for use by the ANU Research School of Earth Sciences.

The Farnham Telescope

Built by Grubb of Dublin in 1886, the Farnham Telescope was donated to the Commonwealth Solar Observatory by the estate of Lord Farnham in 1906 and installed in 1928. 

The telescope had limited use, but it was used to undertake some of the earliest spectroscopic classification of southern stars and in the 1940s, it was used to investigate variable stars. 

In 1957 the Farnham Telescope was fitted with an 8-inch Schmidt camera and subsequently used as a guide telescope for the Schmidt Telescope, which undertook the first deep photographic survey of emission nebulae in the Southern Milky Way.

The Farnham Telescope may just be the luckiest telescope at Stromlo. It survived not only the 1952 bushfire that damaged the Observatory but was also the only telescope to survive the 2003 bushfire that decimated the Observatory. 

After the 2003 bushfire, the telescope was relocated from its dome for use in public outreach.  

The Yale-Columbia Refractor

In the early 1900s around a dozen large (26-inch+) refractors were constructed around the world. One of these was a 26-inch refractor commissioned by Yale and Columbia Universities in 1923 and installed at Johannesburg Observatory in South Africa. It was constructed in the United States, with the lens made by James McDowell of Pittsburgh and the telescope mount and tube made in the Yale University workshops.

In the 1930s the Yale-Columbia Refractor was used to determine the velocities of around 7,000 stars in Omega Centauri, enabling astronomers to calculate the mass of this giant cluster, determining it to be several million times the mass of the Sun. 

In 1952 the Refractor was relocated to Mount Stromlo Observatory where it was widely used from 1956 for astrometry, using photographic plates to measure the exact position of stars. 

After Yale and Columbia Universities donated the telescope to Mount Stromlo Observatory in 1963, it was used to assist with the planning of NASA’s Voyager missions to the outer planets by taking photographs of the moons of Jupiter and Saturn. From 1977 to 1992, the telescope was used by the University of Virginia to extend its parallax program to the Southern Hemisphere.

The Yale-Columbia Refractor was destroyed in the 2003 bushfires. Its burnt-out dome remains in situ. The badly damaged objective lens and part of the telescope tube were saved for display, and the setting circles and part of the main axis were incorporated into a commemorative sculpture. 

The 74-inch Reflector

The 74-inch Reflector was the largest telescope at Mount Stromlo Observatory, built by Grubb-Parsons in the UK in 1952 and operational from 1955. At the time, it was the equal fourth largest telescope in the world and the largest telescope in the Southern Hemisphere until 1974.  

The telescope used a 74-inch Pyrex glass mirror that could collect 85,000 times more light than a human eye, and a camera capable of imaging objects more than ten million times fainter than the human eye could see. The telescope was mounted on two axes to capture both north-south and east-west movement. 

To accompany the 74-inch Reflector, Stromlo’s Ted Dunham constructed a Coude spectrograph. The Coude design required extensive excavations of solid rock, undertaken with small highly-controlled blasts to prevent damage to the adjacent 74-inch Reflector.  

In its first years of operation, the 74-inch Reflector required two people to operate it – an observer who handled the instruments attached to the focal position in use and an assistant who drove the dome and monitored the weather. The latter was eventually replaced by a computer.  

The 74-inch Reflector made a significant contribution to our understanding of the life cycle of stars. In 1982 it was used to determine that the star CD-38245 is so old that it is comprised almost entirely of gases remaining from the Big Bang. The telescope was also used in studies of quasars and white dwarfs as well as searching for exploding stars and planets beyond our solar system. 

The 74-inch Reflector was destroyed in the 2003 bushfires, although its burnt out dome remains in situ.  

The Great Melbourne Telescope (50-inch Telescope)

The Great Melbourne Telescope (GMT), completed in 1868, was one of numerous large (1m+ diameter) telescopes constructed c. late 1800s to mid-1900s to study nebulae in the southern sky. 

Its initial design was highly flawed. It was heavy and unbalanced and housed in a shed susceptible to wind and vibrations. Its mirrors tarnished quickly and lost their shape. The drive system was inadequate for photographic use, and it was unable to photograph anything fainter than the Moon. Consequently, it received little use until it was moved to Stromlo from the Melbourne Observatory and rebuilt, with its heavy metal mirrors replaced by aluminium-coated glass mirrors. The mounting was also rebuilt, and the telescope was housed in a dome. The optics were redesigned to support photography and spectroscopy. 

The GMT was used between the 1950s and 1970s before being rebuilt c. 1989-1991 for use in the MACHO (Massive Astronomical Compact Halo Objects)project, researching dark matter by monitoring the light intensity of millions of stars in the Small and Large Magellanic Clouds and Galactic Bulge Fields. 

In 2000 the GMT was converted to an Automatic Patrol Telescope (APT) and used to survey the outer Solar System for asteroids. This conversion allowed the telescope to be computer controlled without the need for a human operator. 

Prior to its destruction in the 2003 bushfires, the GMT was used for the Skymapper project, with the aim of generating a digital map of the southern skies. Following its destruction, the Skymapper project was transferred to Siding Spring Observatory.

The Uppsala Dome and Uppsala-Schmidt Telescope

Built between 1955-1956, the Uppsala Dome housed a 20-inch Schmidt telescope under the operation of Sweden's University of Uppsala. Equipped with a very fast wide-angle survey camera, the Uppsala-Schmidt Telescope developed more than two thousand photographic plates of the Southern Milky Way and the Magellanic Clouds. 

The telescope was installed at Mount Stromlo Observatory in 1957 and in October that year it captured the first astronomical image of Russia’s Sputnik1 – the world’s first artificial satellite.

As Canberra’s light pollution worsened, in 1981 the decision was made to relocate the telescope to Siding Spring Observatory where it was used to observe comets and asteroids. In 2007, the telescope was used by Robert McNaught to discover the Great Daylight Comet (C/2006 P1).

The Uppsala Dome remained at Mount Stromlo Observatory for use as the headquarters of the Canberra Astronomical Society. The building was extensively damaged in the 2003 bushfires and was subsequently demolished.

The Schmidt Telescope was donated to the Tamworth Regional Astronomy Club in 2020.