David Dunlap Observatory

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David Dunlap Observatory
Dunlap Observatory.jpg
The 74-inch (1.9 m) telescope at the David Dunlap Observatory
Organization University of Toronto (1935–2008)
Royal Astronomical Society of Canada (2009–)
Code 779
Location Richmond Hill, Ontario, Canada
Coordinates 43°51′44″N 79°25′21″W / 43.86222°N 79.42250°W / 43.86222; -79.42250
Altitude 224 m (735 ft)
Weather 67% clear nights[1]
Established 31 May 1935


Telescope 1 1.88 m reflector
Telescope 2 0.6 m Cassegrain
Telescope 3 0.5 m Cassegrain
Commons page Related media on Wikimedia Commons

The David Dunlap Observatory (DDO) is a large astronomical observatory site just north of Toronto in Richmond Hill, Ontario, housed on a 189-acre (76 ha) estate. Formerly owned and operated by the University of Toronto from its establishment in 1935 until 2008, the observatory is now managed by the Royal Astronomical Society of Canada, Toronto Centre. 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 included a small radio telescope as well.

The DDO is the site of a number of important 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.[1] Located on a hill, yet still relatively close to sea level at 730 feet (220 m) altitude, and now surrounded by subdivisions, its optical astronomy ability has been reduced as compared to other remote observatory sites around the world.



Concept sketch of David Dunlap Observatory

The DDO owes its existence almost entirely to the efforts of one man, Clarence Chant.[2] 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.[3] 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.[2]

Chant joined the Astronomical and Physical Society of Toronto in December 1892; it was eventually renamed the Royal Astronomical Society of Canada in 1902. Chant became president of the Society, serving between 1904 and 1907.[3] 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.[3]

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 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 with them to their new location on Bloor Street. 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.[3][4]

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 the perfect location, a 10-acre (40,000 m2) 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 the outbreak of World War I put the project on hold, and in 1919 it was cancelled outright.[3]

Dunlap involvement[edit]

Chant then turned to the local business community in hopes of finding funding. Similar collaborations had been very successful in the United States, but Chant found an entirely different reception in Canada and nothing seemed forthcoming.[3] His fortunes changed in 1921 when Chant delivered a public lecture on Comet 7P/Pons-Winnecke, which had recently been visible in Canada. One of the attendees was mining executive David Dunlap (1863–1924), who was bitten by the astronomy bug as a result of the lecture, and expressed an interest in Chant's efforts to build a large observatory. Before making any firm financial commitment, however, Dunlap died in October 1924 at age 61 (also see 70207 Davidunlap). Chant approached his widow, Jessie Dunlap, in late 1926 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."[3]

By this point the original site was well within the rapidly growing city's lit areas, and no longer suitable for astronomy. A site much further from the city was needed, to ensure it too would not be crowded out. 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 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. When Chant took Dunlap to see the site for the first time, she stated "this is the place!" and authorized its purchase for C$28,000.[3]


The view of David Dunlap Observatory in 1935. Observatory House is visible in the upper left.
The administration building, with two of the observatory's telescopes built on top. The building's third dome is just out of sight behind the trees on the left.

Chant immediately started ordering a telescope, selecting a 74-inch (1.9 m) instrument from Grubb, Parsons and Company in England. This would make it the second largest telescope in the world, second only to the 100-inch (2.5 m) instrument at Mount Wilson Observatory.[3] It was, however, only slightly larger than the one that had recently gone into service for the Dominion Astrophysical Observatory in British Columbia, at 72 inches (1.8 m). The observatory building itself started construction, and the eighty-ton sixty-one-foot (18.6 m) copper dome was built by Grubb and Parsons in 1932 and arrived in 1933. The administration building, a few hundred feet from the main observatory, also started construction. The 76-inch (1.9 m) mirror blank (the two outermost inches (5 cm) of the mirror are not used) was supplied by Corning Incorporated and cast in Pyrex from a batch of glass that Corning also used to produce the 200-inch (5.1 m) mirror for Palomar Observatory. Chant and Mrs. Dunlap attended the pouring of the mirror at the factory in Corning, NY in June 1933. The mirror was annealed, then shipped to Grubb-Parsons in England for polishing. The telescope was completed in time for the finished mirror's return in May 1935.[3]

The official opening was on 31 May 1935, Chant's 70th birthday. The opening ceremony was attended by notables such as Sir Frank Dyson, former Astronomer Royal, and former Prime Minister William Lyon Mackenzie King, who praised the Observatory as "a gift to science all over the world." Chant retired the same day and moved into Observatory House, the original pre-Confederation farmhouse just to the south of the administration buildings, where he spent his remaining years. In May, 1939 the train carrying King George VI and Queen Elizabeth, the Queen Mother on their cross-Canada tour paused on the railway below the observatory, the largest telescope in the commonwealth.[5]

Grubb-Parsons built four more 1.88-metre telescopes with similarities to the instrument in Richmond Hill: for Radcliffe Observatory near Pretoria, Mount Stromlo Observatory in Australia, Helwan Observatory in Egypt, and an observatory in Okayama Prefecture in Japan.[6] The South African instrument was disassembled and moved to Sutherland, Northern Cape in the 1970s because of light pollution.[7] The original telescope mirror at Helwan was replaced by Zeiss in 1997, and the telescope at Mount Stromlo was destroyed by fire in 2003.[8] A 1.93-metre Grubb-Parsons telescope at Haute-Provence Observatory with a higher-resolution spectrograph was used to discover an extrasolar planet orbiting the star 51 Pegasi in 1995.[9]

The three smaller domes on the top of the DDO administration building are used for smaller instruments. Soon after the observatory opened in 1935, a 50 cm Cassegrain reflector telescope was installed in the southern dome. The 6-inch (150 mm) Cooke Refractor had been out of use since the Meteorological Office had given it to Hart House, but it was little used and was moved into the northern dome in 1951 to be used by undergraduates. Much later, in 1965, a similar 60 cm Cassegrain was added to the central dome.[3]


From 1946 to 1951 the observatory director was Frank Scott Hogg, who was joined at the DDO by his wife Helen Sawyer Hogg. After her husband's death, Helen continued at the observatory, surveying globular clusters to gauge their distance, publishing a major catalog of variable stars in clusters.[10] Her weekly 'With the Stars' column in the Toronto Star was published from 1951 to 1981. In 1959 and 1966 staff astronomer Sidney van den Bergh composed a database of dwarf galaxies known as the David Dunlap Observatory Catalogue.[11]

In collaboration with the Department of Electrical Engineering, Dr. Donald MacRae established a radio astronomy observatory on the observatory grounds in 1956.[2] The DDO work led to the 1963 measurement of the absolute flux density of Cassiopeia A at 320 MHz, a radiometric standard. The DDO also built an 18 m radio telescope in Algonquin Park in northern Ontario, co-locating it at the site of the larger Algonquin Radio Observatory. This instrument was actively used until 1991, when budget cuts led to it being abandoned. It was later used by a private group as part of a SETI project, Project TARGET,[12] and has reported moved to a site outside Shelburne, Ontario.

In 1960 observatory operations formed the narrative framework of the NFB short film Universe. The film was nominated for the 33rd Academy Awards in the category of best documentary, short subject in 1961. Universe was shown at the 1964 New York World's Fair where it was seen by Stanley Kubrick and Arthur C. Clarke, who were starting work on the film that eventually became 2001: A Space Odyssey. Universe featured future DDO director Donald MacRae and was narrated by Stanley Jackson.[13][14]

University of Toronto Professor Tom Bolton was hired at the DDO in 1970. In 1971 he used data from the Uhuru X-ray observatory, and Naval Research Laboratory sounding rockets launched from White Sands Missile Range[15] to find the optical companion star to the X-ray source Cygnus X-1. Those X-ray telescopes had a certain degree of accuracy, but follow-up optical-wavelength studies of possible companions were required to eliminate a shortlist of many stars in the same area of sky. Bolton observed the star HDE 226868 independently of the work by Louise Webster and Paul Murdin, at the Royal Greenwich Observatory, who could not prove that star was Cygnus X-1's optical companion. The high dispersion of the 74-inch (1.9 m) telescope's spectrograph, combined with the 74-inch (1.9 m) aperture was adequate to prove the star was the source of the X-ray emissions and that its behaviour was inconsistent with a normal eclipsing star.[16][17]

Shifting locations[edit]

With the rapid growth of university funding in the 1960s more offices were being built in the downtown campus, and with the opening of the McLennan Labs more and more of the department moved into the new facilities. The Administration Building at the DDO headquartered the Astronomy Department until the 1960s, although the weekly department meetings continued to be held there until 1978. The main library was shifted downtown in 1983. The Cooke Refractor, now almost unused, was later donated to the Canada Science and Technology Museum in 1984.[2]

The main reflector at the DDO remained a major instrument into the 1960s, but in the end even the "remote" location Chant had selected was being encroached on by urban sprawl. Although some consideration was given to moving the telescope to a new site, in the end it was decided the funds would be better spent on a smaller instrument in a much better location. This led to the building of a 60 cm instrument at Las Campanas in Chile in 1971, creating the University of Toronto Southern Observatory (UTSO). It was at this location that University of Toronto telescope operator Ian Shelton discovered Supernova 1987A, the first supernova visible to the naked eye in more than 350 years.[18] The UTSO was later closed in 1997 to re-allocate funds to a share of the Gemini Observatory, and the 60 cm telescope was moved to El Leoncito in Argentina, where the University has a 25% share in observation time.[2] While University operations continued at the DDO, international observers used about 50% of observing time there.

Closure, sale and re-opening[edit]

By the mid-1990s, the observatory remained the largest single mirror in Canada, but it was considered small by modern standards.[19] The cutting edge of Canadian university astronomy studies was involved in some of the world's largest observatories: the James Clerk Maxwell Telescope, the Canada-France-Hawaii Telescope, the Atacama Large Millimeter Array and the Gemini Observatory. None of these telescopes are located in Canada. After the UTSO was closed, in 1998 the Canadian Astronomical Society, a society of university astronomers, published a long range plan emphasizing the study of the origins of structure in the universe,[20] a task well-suited to cutting-edge telescopes but ill-suited to the DDO. The long-range plan suggested the future of observatories such as the DDO lay in public outreach programs and training. In 2005 Canadian universities joined a partnership to build the Thirty Meter Telescope, expected to cost more than $1 billion.[21]

In September 2007, the University stated it planned to sell the DDO property owing to light pollution.[22] The university's governing council voted on the issue during the week of 1 November 2007, and agreed to sell the site to the highest bidder. The 75 hectares (190 acres) of land in the midst of a very large subdivision area was expected to fetch $100 million, some of which the university planned to use to found a Dunlap Institute to continue astronomical research. The sale was called a "cash grab" by Richmond Hill Mayor David Barrow, also stating "There's all kinds of opportunities here that they're just blowing off because they want the money. After 70 years, they're just walking away without looking over their shoulder at what they're leaving behind. That's our disappointment."[23]

For the purposes of the sale, the land was partitioned into a 71 ha Parcel A and a 5 ha Parcel B, upon which sits the Elvis Stojko Hockey Arena and also a park with a 200-metre-wide solar system model. The arena is leased by the Town, now from the new owner, until 2015.[24]

At the end of June 2008, the university completed the sale of both parcels of the property to Corsica Development Inc., a subsidiary of Metrus Development Inc. for $70 million, a lower price than expected. Observatory staff were laid off and faculty reassigned to the downtown St. George campus.[25] The Town of Richmond Hill planned a hearing with the Conservation Review Board of Ontario to argue for protection of the western 48% of the property including the observatory buildings under the Ontario Heritage Act; at the hearing, the Richmond Hill Naturalists argued for 100% designation of the property, all the buildings and their contents,[19][26] and the Observatory Hill Homeowners Association argued for the protection of the heritage woodlots and arboretums. Corsica Development Inc. was also represented before the CRB. Preliminary hearings took place on September 3 and October 15, 2008. Corsica Development Inc. is administered by Metrus in conjunction with The Conservatory Group and Marel Contracting.[27]

The Conservation Review Board hearing to determine the extent of the Cultural Heritage Landscape designation to be afforded to the Dunlap site took place in Richmond Hill between January 15 to 23, 2009, and the Board recommendation was published on June 4.[28] The Board recommended preservation of the observatory buildings and up to 80% of the property as a cultural heritage landscape. On September 29, 2009 Richmond Hill Town Council voted unanimously in favour of the designating by-law.[29] The Town proceeded with a number of public meetings and reports in late 2009 to craft guidelines for the conservation, planning and design of the property. Corsica Development Inc. undertook an archaeological survey of the property.[30] On April 15, 2010 stemming from an incident on the property in November 2009, Corsica Development Inc. pleaded guilty in York Region court to 17 counts of cutting a tree without a permit and was issued a fine of $44,880.[31] The company also planted 100 new trees on the property as part of the judgment.[32]

In January 2009, Corsica published the website observatoryhill.ca describing the property, stating, "[We] are in the process of looking for an astronomy club to occupy the observatory and welcome proposals for consideration."[33] On April 22, 2009 Corsica and the Royal Astronomical Society of Canada announced an agreement allowing the RASC to provide public education and outreach programs at the observatory, and to operate the 1.88m telescope.[34] On June 14, the RASC Toronto Centre published the website www.theddo.ca,[35] to make tickets available for public astronomy nights at the observatory starting on July 18. Astronomy events at the observatory continue, such as Perseid meteor shower events that draw high attendance and media coverage.[36] These new operations continued through 2014, combined with opportunities such as use of the observatory for location shoots of the Syfy (formerly Sci-Fi Channel) series Warehouse 13 and the NBC television series Hannibal.[37]

Dunlap Institute for Astronomy & Astrophysics[edit]

In early 2009, coincident with the International Year of Astronomy the University of Toronto started several initiatives connected with the foundation of the Dunlap Institute. The University's Department of Astronomy and Astrophysics, which already had close ties with the Canadian Institute for Theoretical Astrophysics (CITA) announced it was seeking a director for the Dunlap Institute.[38] At the same time Ivan Semeniuk, a well-known Canadian science journalist, joined the Dunlap Institute as Journalist-in-Residence.[39] Dr. Ray Jayawardhana, Canada Research Chair in Observational Astrophysics, announced a series of high-impact advertisements on subways and other vehicles of the Toronto Transit Commission linking to the Institute's World Wide Web presence at www.coolcosmos.net. The Dunlap Institute, along with CITA and the Department of Astronomy and Astrophysics co-hosted the 2009 annual meeting of CASCA in May,[40] including the annual Helen Sawyer Hogg Lecture sponsored jointly with the Royal Astronomical Society of Canada.[41] The lecture was given by Lawrence M. Krauss. In July 2010 James R. Graham was announced as the new Dunlap Institute director. Further Dunlap Institute lectures through 2014 were given by Dr. Jill Tarter, Dava Sobel, Mike Brown and Neil DeGrasse Tyson. In 2009 CASCA named Mr. and Mrs. Dunlap's two grandsons Patrons of the Society,[42] and they received honorary degrees from the university in 2011.[43] The Dunlap Institute has conducted annual undergraduate and graduate "summer school" programs working with astronomical instrumentation, starting in 2012.[44] On 5 June 2012 the Dunlap Institute hosted a Transit of Venus public observing event which filled the university's historic Varsity Stadium. In the same year, Dunlap Institute astronomers began an ongoing survey of extra-solar planets from the Canadian Arctic at the PEARL Laboratory near Eureka, Nunavut.[45] The Dunlap Institute participated in the Gemini Planet Imager collaboration to directly image extrasolar planets in Chilé. In 2013 CASCA inaugurated the Dunlap Award for Innovation in Astronomical Research Tools, to be awarded to a Canadian astronomer or astronomers in alternate years.[46]


The DDO main instrument was the second largest telescope in the world when it began operation in 1935, slipping to third with the opening of the Hale Telescope in 1948. The thee largest telescopes in 1935 were:

# Name /
Image Aperture Altitude First
Special advocate
1 Hooker Telescope
Mount Wilson Obs.
100inchHooker.jpg 100 inch
254 cm
1742 m
(5715 ft)
1917 George Ellery Hale
Andrew Carnegie
2 David Dunlap Observatory Dunlap Observatory.jpg 74 inch
188 cm
224 m
(735 ft)
1935 Clarence Chant
3 Plaskett telescope
Dominion Astrophysical Obs.
Dominion Astrophysical Observatory front.jpg 72 inch
182 cm
230 m
(755 ft)
1918 John S. Plaskett

See also[edit]



  1. ^ Polaris - The Story Continues Photoelectric Photometry Newsletter, American Association of Variable Star Observers, May 1998
  2. ^ a b c d e Fernie 2000.
  3. ^ a b c d e f g h i j k Russell 1999.
  4. ^ Beattie, Brian (1982). "The 6-inch (150 mm) Cooke Refractor in Toronto". Journal of the Royal Astronomical Society of Canada. 76 (2): 109–128. Bibcode:1982JRASC..76..109B. 
  5. ^ "Scheinman Report", Town of Richmond Hill, June 17, 2008, SRPD.08.097
  6. ^ http://www.oao.nao.ac.jp/en/
  7. ^ Assa Historical Section
  8. ^ "History". Research School of Astronomy & Astrophysics, Australian National University. 
  9. ^ Mayor, M; Queloz, D. "The discovery of 51 Pegasi at Haute-Provence Observatory" (PDF): 1–10. 
  10. ^ Hogg, Helen Sawyer (1973). "A Third Catalog of Variable Stars in Globular Clusters Comprising 2199 Entries" (PDF). Publications of the David Dunlap Observatory. 
  11. ^ van den Bergh, Sidney (1959). "A catalogue of dwarf galaxies". Publications of the David Dunlap Observatory: 147–150. Bibcode:1959PDDO....2..147V. 
  12. ^ "A Brief SETI Chronology". SETI League. 
  13. ^ "Universe". National Film Board. 
  14. ^ Seaquist 2006.
  15. ^ personal communication with Professor Bolton, Nov. 28, 2007
  16. ^ Bolton, C. T. (1972). "Identification of Cygnus X-1 with HDE 226868". Nature. 235 (2): 271–273. Bibcode:1972Natur.235..271B. doi:10.1038/235271b0. Retrieved 2008-03-10. 
  17. ^ Rolston, Bruce (10 November 1997). "The First Black Hole". The Bulletin. University of Toronto. Archived from the original on 2008-05-02. 
  18. ^ "IAUC4316: 1987A, N. Cen. 1986". 24 February 1987. 
  19. ^ a b "Black holes: The Canadian connection". Quirks and Quarks. CBC. 2008-04-18. Retrieved 2008-07-05. 
  20. ^ The Origins of Structure in the Universe (Technical report). National Research Council (Canada). 1998. 
  21. ^ "Canada and the Thirty Meter Telescope". TMT. 
  22. ^ Brown, Louise (11 September 2007). "U of T Observatory Likely To Be Sold". Toronto Star. 
  23. ^ Gorrie, Peter (2 November 2007). "Observatory Sale Plan Angers Town". Toronto Star. 
  24. ^ Fleischer, David (20 March 2008). "'Sad' Arena May Be Lost, Stojko Says". Richmond Hill Liberal. 
  25. ^ Wagler, Jenny (2008-07-03). "Dunlap Observatory Closing Sparks Anger, Frustration". National Post. Retrieved 2007-07-05. 
  26. ^ "Richmond Hill Naturalists". 
  27. ^ Fleischer, David (7 August 2008). "Metrus took 10 months to secure David Dunlap land". Richmond Hill Liberal. 
  28. ^ "Re: Intention to Designate the Property known as the David Dunlap Observatory, 123 Hillsview Drive, Richmond Hill (CRB File 2007-12)" (PDF). Conservation Review Board. 
  29. ^ "Minutes of Richmond Hill Town Council meeting" (PDF). 29 September 2009. 
  30. ^ "Draft Phase 2 Archaeological Report". Observatory Hill. 26 May 2010. 
  31. ^ "What is the DDO?". Town of Richmond Hill. 
  32. ^ "Replanting of removed trees begins on DDO site". Post City Magazines. June 2010. 
  33. ^ "Future". ObservatoryHill.ca. Observatory Hill. 17 February 2009. Archived from the original on February 17, 2009. 
  34. ^ "Clear Skies Ahead for Canada's Largest Telescope" (PDF). Royal Astronomical Society of Canada Toronto Centre. 
  35. ^ Welcome to the David Dunlap Observatory, David Dunlap Observatory website.
  36. ^ "Thanks to the more than 2000 people who brought their lawn chairs, blankets, binoculars and enthusiasm to our Perseid Meteor Night". Royal Astronomical Society of Canada Toronto Centre. 
  37. ^ "In the Community". The David Dunlap Observatory. 
  38. ^ Reinhardt Postdoctoral Fellowship in Astrophysics, "Director, Dunlap Institute for Astronomy and Astrophysics
  39. ^ "Ivan Semeniuk's Embedded Universe"
  40. ^ "CASCA 2009 University of Toronto 2009 May 26-29"
  41. ^ "Helen Sawyer Hogg Memorial Lecture"
  42. ^ "Patrons of the Society"
  43. ^ "U of T awards honorary degrees to philanthropists, public servants"
  44. ^ Oakes, Andrew (February 2014). "The Dunlap Institute's 2013 Summer School". Journal of the Royal Astronomical Society of Canada. 
  45. ^ Law, Nicholas; et al. (August 2012). "New Exoplanet Surveys in the Canadian High Arctic at 80 Degrees North". Instrumentation and Methods for Astrophysics. arXiv:1208.5769Freely accessible. 
  46. ^ "Dunlap Award for Innovation in Astronomical Research Tools". Canadian Astronomical Society. 


Further reading[edit]

  • The Cold Light of Dawn: A History of Canadian Astronomy, Richard A. Jarrell, University of Toronto Press, 1988, ISBN 978-0-8020-2653-8

External links[edit]

Coordinates: 43°51′47″N 79°25′22″W / 43.862954°N 79.422687°W / 43.862954; -79.422687