Our History and Heritage
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The Dominion Astrophysical Observatory in which you are standing consists of two professional telescopes and the Centre of the Universe. Visitors’ Centre.
The DAO’s 1.83m (72in) reflector was the largest operational telescope whn completed and the second largest telescope in the world for many years. It is now named for its founder and designer, John Stanley Plaskett.
In the 1930s, Dr Helen Sawyer Hogg identified 132 variable stars in the globulr cluster M2. Her ground-breaking work with the Plaskett Telescope, which she continued in Torono, helped us understand the size and structure of our home galaxy, the Milky Way.
She was one of the first astronomers to travel to the Southern Hemisphere to make observations. She wrote the book “The Stars Belong to Everyone” and a newspaper column which popularized astronomy.
Crucial data about the basic parameters of stars such as their mass and temperature was acquired by Dr Plaskett and his colleagues. Work in this area continues to the present day, including information on the magnetic fields and chemical composition of stars.
The Plaskett Telescope is still used every clear night, determining the orbits of comets and asteroids, studying exploding stars (supernovae) in distant galaxies, and studying the magnetic fields and compositions of stars.
With modern detectors the telescope is approximately 10000 times more sensitive than in 1918, and is fully automated for remote operation.
Staff member Andrew McKellar’s expertise in spectroscopy led to his discovery in 1940 of molecules in interstellar space, and he measured their temperature as 2.7 degrees above absolute zero.
He confirmed the existence of CN cycle, the most prominent nuclear reaction in stars more massive than the sun.
Dr McKellar accomplished much before his early passing at age 50. The 1.2m/48 in telescope is dedicated to spectroscopy. Its main instrument is named for him.
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Dr Andrew McKellar determined in 1940 that carbon-based molecules existed in interstellar space, and measured their temperature at 2.4 degrees above absolute zero.
The source of this puzzling temperature was revealed two decades later to be caused by heat left over from the Big Bang.
Work at the DAO continued to focus on improving our understanding of stars, including their mass, luminosity, and chemical composition.
Dr Ann Underhill wrote the first computer program that simulated the atmospheres of stars at a time when other researchers did numerical calculations on hand-cranked adding machines! Her work was augmented by that of Dr Jean McDonald also did ground-breaking work at the observatory in the mid-50s, modelling stellar atmospheres using the University of Toronto’s systems.
Astronomers here expanded on the pioneering work by Plaskett and Pearce in the 20s and 30s by further defining the rotation of the Milky ay at different distances from the Galaxy’s centre, and in understanding the gas and dust clouds between the stars. They also did census of the solar neighbourhood and measured how dust clouds affected our view of our neighbours.
Dr Alan Batten, starting in 1959, sought to complete the extensive survey of multiple star systems that Plaskett began as long ago as 1907. He published the definitive atlases of the binary stars until the 1980s.
He discovered that the majority of ‘stars’ are in fact in multiple systems, too close to distinguish with the naked eye.
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In 1983 David Crampton and John Hutchings at the DAO, together with Ann Cowley, confirmed the existence of stellar mass black holes, finding LMC X-3, an -Ray source in the Large Magellanic Cloud behaved as expected for a compact unseen object orbiting and stripping material off a companion bright star.
Then in 1984 Campbell, Crampton and University of Victoria radio astronomer Ann Gowever found that quasars, searingly bright objects at huge distances, were actually located at the centres of galaxies. These were ater to be associated with massive black holes.
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The Radial Velocity technique for detecting planets superposed the spectrum of a chemical element well understood on earth on the spectrum of a star thought to have planets orbiting it.
Measuring movement of the lines of the unknown star relative to the known chemical element allowed the detection of minute changes in the radial velocity of the star - which, if periodic inferred the existence and orbit of a planet moving around it.The technique started with a conversation between Bruce Campbell and Gerhard Herzberg. Co-developed by UBC and UVic astronomers Campbell, Walker, and Yang, it led to the discovery of hundreds of exoplanets. It was first tested on the spectrograph here at DAO
The use of this technique on the Canada France Hawaii Telescope led the suggestion in 1988, later confirmed, of a planet around the star Gamma Cephei. Had it been confirmed by the original sighting it would have been the first exoplanet ever detected.
The Gemini Planet Imager, an extreme adaptive optics instrument, was delivered by the Herzberg Institute and its partners to the Gemini South telescope to search for planets moving around nearby stars.
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Canadian astronomers in the 1960s began to feel the need for bigger telescopes, particularly as many universities in Canada began doing cutting-edge research in astrophysics involving faint objects at great distances.
Canada’s partnering in the 3.6m Canada France Hawai’i Telescope (CFHT) project, completed in 1979, began an era of international partnerships in building large telescopes and innovative instrumentation.
Canada helped in building the two 8.2 meter Gemini Telescopes- one in Hawai’i (North) and one in Chile (South) in the 1990s. Many DAO astronomers and engineers were heavily involved, with Canadian businesses awarded large contracts.
The Gemini Planet Imager, an Adaptive Optics instrument, is installed on Gemin South to search for planets around nearby stars.
The Thirty Meter Telescope (TMT) is a next-generation "extremely large telescope" designed to provide images 12 times sharper than the Hubble Space Telescope and peer into the earliest moments of the universe. Featuring a 30-meter primary mirror composed of 492 hexagonal segments, the TMT aims to solve fundamental mysteries regarding dark matter, the first stars and galaxies, and the atmospheres of exoplanets. However, the project has faced nearly a decade of delays and social conflict. While Mauna Kea in Hawaiʻi remains the preferred site due to its high altitude and atmospheric clarity, construction has been stalled since 2019 due to sustained opposition from Native Hawaiian practitioners who consider the mountain sacred. As a result, the TMT International Observatory (TIO) has maintained a "Plan B" at La Palma in the Canary Islands, though a final decision to relocate has not yet been made as of early 2026.
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Innovative instruments designed to get the most from telescopes are created in Victoria as part of the Astronomy Technology Program. The program grew out of the CFHT project It began producing exceptional new instruments to get the most out of telescopes.
Some of these devices include adaptive optics, which sharpen images by correcting for our atmosphere’s turbulence.
An experimental device that corrects for the blurring effects of the Earthś turbulent atmosphere was designed and built at the DAO, then installed at CFHT in 1988.
HRCAM (High Resolution Camera) allowed astronomers to get images nearly as sharp as if the telescope was in space, for a small fraction of the cost.
The technology was incorporated into spectrographs that put Canadian astronomers and their partners atthe forefront of studies of distant galaxies.
Engineering performed in Victoria includes optical, mechanical, and electrical engineering. An example is the Gemini Multi Object Spectrograph, built in Victoria, and in Durham, UK, for the Gemini Telescopes.
GMOS can acquire hundreds of spectra at once. By contrast, it took Plaskett and his colleagues years to collect 40 spectra in the 1920s!
Software called DAOPHOT developed here by Dr. Peter Stetson was critical to establishing the distance scale of the Universe based on images from the Hubble Space Telescope in the 1990s.
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Founded as one of the three Hubble Space Telescope Data archives, the Canadian Astronomy Data Centre (CADC) is now an archiv for data from more than a dozen telescopes.
Astronomers perform data mining to extract new information from existing observsations. Resources include deep surveys of the sky at different wavelengths.
Astronomical objects change over time, so that data from earlier periods also has special value.
The CADC played a key role in the establishment of CA*NET, the precursor of the Internet in Canada.
The network was needed by astronomers to move large amounts of data from the Hubble Space Telescope to researchers across Canada.
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The Atacama Large Millimeter/submillimeter Array (ALMA) is a revolutionary instrument consisting of of 66 12m wide dishes that work together . ALMA collects data at wavelengths from 0.3 mm to 9.6 mm.
It can detect details 10x as sharp as the Hubble Space Telescope images and can perform spectroscopy. ALMA observes the heavens from a high, arid plane in Chile.
Its dramatic leap forward in millimeter-wave astronomy complements observations from of telescopes optimized for other wavelengths.
ALMA can be used to study the birth of stars, planets, galaxies, and the early universe. Its resolution is high enough to show features around stars such as spiraling jets of material around an old red giant star. It has created images of protoplanetary disks around young newly formed stars - actual distant solar systems in the making.
The Square Kilometre Array (SKA) is an international project to build the world’s largest and most sensitive radio telescope, designed to revolutionize our understanding of the universe. Managed by the SKA Observatory (SKAO) and headquartered in the United Kingdom, the project consists of two massive telescope arrays across two continents: SKA-Low, featuring over 130,000 dipole antennas in Western Australia, and SKA-Mid, which will comprise nearly 200 parabolic dishes in South Africa’s Karoo region. By operating across a vast range of radio frequencies, the SKA will allow astronomers to peer back to the "Cosmic Dawn" when the first stars and galaxies formed, test Einstein’s theories of relativity in extreme environments, and search for the chemical signatures of life on distant planets.
Canada officially became a full member of the SKAO in June 2024, backed by a federal investment of approximately $285 million over eight years. This partnership secures a 6% observing share for Canadian researchers, ensuring they remain at the forefront of astronomical discovery. Beyond funding, Canada is a primary technical contributor; the National Research Council (NRC) and industry leader MDA Space are developing the SKA-Mid Correlator/Beamformer—the "brain" of the South African array—while Nanowave Technologies provides the high-performance cryogenic low-noise amplifiers essential for signal clarity.
To manage the vast quantities of data, the SKAO will be supported by a global network of SKA Regional Centres (SRCs). Canada will host SRC in the Americas, providing user data access, support and archive services by building on the Canadian Network for Astronomical Research (CANFAR) science platform, which is maintained by the NRC’s Canadian Astronomical Data Centre (CADC) here at the DAO.