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David Dunlap Observatory
The David Dunlap Observatory (DDO) is an astronomical observatory site in Richmond Hill, Ontario, Canada. Established in 1935, it was owned and operated by the University of Toronto until 2008. It was then acquired by the city of Richmond Hill, which provides a combination of heritage preservation, unique recreation opportunities and a celebration of the astronomical history of the site. Its primary instrument is a 74-inch (1.88 m) reflector telescope, at one time the second-largest telescope in the world, and still the largest in Canada. Several other telescopes are also located at the site, which formerly also included a small radio telescope. The telescope was driven by the vision of astronomer Clarence Chant, shared by businessman David Alexander Dunlap – whose family provided financial support after Dunlap's death in 1924. The scientific legacy of the David Dunlap Observatory continues in the Dunlap Institute for Astronomy & Astrophysics, a research institute at the University of Toronto established in 2008.
The DDO is the site of a number of important scientific studies, including pioneering measurements of the distance to globular clusters, providing the first direct evidence that Cygnus X-1 was a black hole, and the discovery that Polaris was stabilizing and appeared to be "falling out" of the Cepheid variable category. Located on a hill, yet still relatively close to sea level at 730 feet (220 m) altitude, and now surrounded by urban settlement, its optical astronomy ability has been reduced as compared to other remote observatory sites around the world. On 31 July 2019, the DDO was accepted by the National Historic Board as a National Historic Site of Canada.
The DDO owes its existence almost entirely to the efforts of Clarence Chant. Chant had not shown an early interest in astronomy, but while attending University College, University of Toronto, he became interested in mathematics and physics, eventually joining the university as a lecturer in physics in 1892. Over the next several years he worked as a schoolteacher and civil servant. During a later leave of absence he earned his PhD from Harvard University and did postdoctoral work in Germany.
Chant joined the Astronomical and Physical Society of Toronto in December 1892; it was renamed the Royal Astronomical Society of Canada in 1902. Chant became president of the Society, serving between 1904 and 1907. Throughout the 1890s, Chant was concerned about how little the university did for astronomy, and in 1904 he proposed adding several undergraduate courses for fourth-year students, and six such courses were added to the 1905 calendar.
With courses now officially on the books, Chant started looking for a proper telescope. Previously the university had hosted the Toronto Magnetic and Meteorological Observatory, which had been run by the Meteorological Office of the Ministry of Marine and Fisheries. The observatory, built in 1840, had contained the high-quality 6-inch (150 mm) Cooke Refractor, but the Observatory was now surrounded by new university buildings, rendering it useless for astronomy. The Meteorological Office had already decided to abandon the site and turn the building over to the university, but they were taking the telescope to their new location at 315 Bloor Street West. Even if the university had been able to secure time on the instrument, which was highly likely, it was at this time quite a small instrument in comparison to those being built around the world.
The same problem of encroachment that had led to the observatory falling into disuse led Chant to conclude that there was no suitable location on the university grounds for a new observatory, and he started looking for off-campus sites. While looking, he started getting quotes for a new instrument from Warner & Swasey in Cleveland, Ohio, who had provided the mount for the recently opened Dominion Observatory in Ottawa. In 1910 Chant finally found a suitable location, a 10-acre (4.0 ha) plot of land near what is today Bathurst Street and St. Clair Avenue. The land had originally been set aside by the city for the Isolation Hospital, but this was never constructed and it now lay empty. Chant convinced the city to become involved in the Royal Astronomical Observatory, but lack of funds and the outbreak of World War I put the project on hold, and in 1919 it was cancelled outright.
Knowing that similar funding collaborations had been very successful in the United States, Chant turned to the local business community. To promote his plan, Chant often concluded public lectures with a pitch to the audience for a larger observatory for Toronto; this included a 1921 talk on Comet 7P/Pons-Winnecke, which had recently been visible in Canada. One of the attendees was Hollinger Mines co-founder, lawyer David Dunlap (1863–1924), who expressed an interest in Chant's efforts to build a large observatory. However, before making any financial commitment, Dunlap died in October 1924 at age 61 (also see 70207 Davidunlap). In late 1926, Chant wrote to his widow, Jessie Dunlap, with the idea of erecting an observatory as a monument to her husband. Mrs. Dunlap promised to "keep it in [her] heart for consideration, for it appeals to me tremendously."
By this point the chosen site was within the rapidly-growing city, and not suitable for astronomy due to both light pollution. A site much further from the city was needed, to ensure it too would not be crowded out, as well as to reduce the impact of moisture-filled air and fog from Lake Ontario. The first site studied was outside Aurora, Ontario, but it was decided that it was too far from the university for casual travel. Another site near Hogg's Hollow was also studied, but was not easily accessible. The eventual site was selected while Chant was studying topographical maps with fellow astronomer Reynold K. Young, finding a suitable spot north of the city. The site was a short distance east of Yonge Street, and the Canadian Northern Ontario Railway line ran along the western end of the site. It was on Lot 42 on what was Alexander Marsh's farm and orchard. In 1930, when Chant took Dunlap to see the site for the first time, she stated "this is the place!" and authorized its purchase for CA$28,000 (equivalent to $505,000 in 2025).
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David Dunlap Observatory
The David Dunlap Observatory (DDO) is an astronomical observatory site in Richmond Hill, Ontario, Canada. Established in 1935, it was owned and operated by the University of Toronto until 2008. It was then acquired by the city of Richmond Hill, which provides a combination of heritage preservation, unique recreation opportunities and a celebration of the astronomical history of the site. Its primary instrument is a 74-inch (1.88 m) reflector telescope, at one time the second-largest telescope in the world, and still the largest in Canada. Several other telescopes are also located at the site, which formerly also included a small radio telescope. The telescope was driven by the vision of astronomer Clarence Chant, shared by businessman David Alexander Dunlap – whose family provided financial support after Dunlap's death in 1924. The scientific legacy of the David Dunlap Observatory continues in the Dunlap Institute for Astronomy & Astrophysics, a research institute at the University of Toronto established in 2008.
The DDO is the site of a number of important scientific studies, including pioneering measurements of the distance to globular clusters, providing the first direct evidence that Cygnus X-1 was a black hole, and the discovery that Polaris was stabilizing and appeared to be "falling out" of the Cepheid variable category. Located on a hill, yet still relatively close to sea level at 730 feet (220 m) altitude, and now surrounded by urban settlement, its optical astronomy ability has been reduced as compared to other remote observatory sites around the world. On 31 July 2019, the DDO was accepted by the National Historic Board as a National Historic Site of Canada.
The DDO owes its existence almost entirely to the efforts of Clarence Chant. Chant had not shown an early interest in astronomy, but while attending University College, University of Toronto, he became interested in mathematics and physics, eventually joining the university as a lecturer in physics in 1892. Over the next several years he worked as a schoolteacher and civil servant. During a later leave of absence he earned his PhD from Harvard University and did postdoctoral work in Germany.
Chant joined the Astronomical and Physical Society of Toronto in December 1892; it was renamed the Royal Astronomical Society of Canada in 1902. Chant became president of the Society, serving between 1904 and 1907. Throughout the 1890s, Chant was concerned about how little the university did for astronomy, and in 1904 he proposed adding several undergraduate courses for fourth-year students, and six such courses were added to the 1905 calendar.
With courses now officially on the books, Chant started looking for a proper telescope. Previously the university had hosted the Toronto Magnetic and Meteorological Observatory, which had been run by the Meteorological Office of the Ministry of Marine and Fisheries. The observatory, built in 1840, had contained the high-quality 6-inch (150 mm) Cooke Refractor, but the Observatory was now surrounded by new university buildings, rendering it useless for astronomy. The Meteorological Office had already decided to abandon the site and turn the building over to the university, but they were taking the telescope to their new location at 315 Bloor Street West. Even if the university had been able to secure time on the instrument, which was highly likely, it was at this time quite a small instrument in comparison to those being built around the world.
The same problem of encroachment that had led to the observatory falling into disuse led Chant to conclude that there was no suitable location on the university grounds for a new observatory, and he started looking for off-campus sites. While looking, he started getting quotes for a new instrument from Warner & Swasey in Cleveland, Ohio, who had provided the mount for the recently opened Dominion Observatory in Ottawa. In 1910 Chant finally found a suitable location, a 10-acre (4.0 ha) plot of land near what is today Bathurst Street and St. Clair Avenue. The land had originally been set aside by the city for the Isolation Hospital, but this was never constructed and it now lay empty. Chant convinced the city to become involved in the Royal Astronomical Observatory, but lack of funds and the outbreak of World War I put the project on hold, and in 1919 it was cancelled outright.
Knowing that similar funding collaborations had been very successful in the United States, Chant turned to the local business community. To promote his plan, Chant often concluded public lectures with a pitch to the audience for a larger observatory for Toronto; this included a 1921 talk on Comet 7P/Pons-Winnecke, which had recently been visible in Canada. One of the attendees was Hollinger Mines co-founder, lawyer David Dunlap (1863–1924), who expressed an interest in Chant's efforts to build a large observatory. However, before making any financial commitment, Dunlap died in October 1924 at age 61 (also see 70207 Davidunlap). In late 1926, Chant wrote to his widow, Jessie Dunlap, with the idea of erecting an observatory as a monument to her husband. Mrs. Dunlap promised to "keep it in [her] heart for consideration, for it appeals to me tremendously."
By this point the chosen site was within the rapidly-growing city, and not suitable for astronomy due to both light pollution. A site much further from the city was needed, to ensure it too would not be crowded out, as well as to reduce the impact of moisture-filled air and fog from Lake Ontario. The first site studied was outside Aurora, Ontario, but it was decided that it was too far from the university for casual travel. Another site near Hogg's Hollow was also studied, but was not easily accessible. The eventual site was selected while Chant was studying topographical maps with fellow astronomer Reynold K. Young, finding a suitable spot north of the city. The site was a short distance east of Yonge Street, and the Canadian Northern Ontario Railway line ran along the western end of the site. It was on Lot 42 on what was Alexander Marsh's farm and orchard. In 1930, when Chant took Dunlap to see the site for the first time, she stated "this is the place!" and authorized its purchase for CA$28,000 (equivalent to $505,000 in 2025).
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