History of the David Dunlap Observatory

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75th Anniversary Celebration

On May 29th, 2010, nearly 200 visitors joined us for a StarBQ and public viewing night to celebrate the David Dunlap Observatory's 75th anniversary. Clear skies throughout the afternoon allowed our volunteers to show off the sun (safely!) through solar telescopes. In the evening everyone enjoyed a thrilling look at Saturn through the 74-inch telescope as well as virtual strolls along the surface of the moon.

Tireless RASC Toronto Centre member Shawn Lee offers a quick lesson in using planispheres to find objects in the night sky while one of our visitors demonstrates that face-painting isn't always limited to faces. Meantime, Toronto Centre Millie Kupke is the queen of the StarBQ grill.

Archie de Ridder, Manager of the Observatory for 40 years, remains an active part of our education and outreach efforts. Here, Archie cuts the anniversary cake to unanimous approval.

Photos by Sharmin Chowdhury and Michelle Johns

The David Dunlap Observatory and Administration Building

The David Dunlap Observatory is Canada's largest optical telescope with a primary mirror measuring more than six feet (74") in diameter. Constructed in the 1930s, the Observatory is located in the heart of Richmond Hill, Ontario. The building is 61 feet in diameter and weighs 80 tons. The telescope itself weighs 23 tons (without its primary mirror).

The property also includes an administration building designed by architects Mathers and Haldenby which includes three additional domes.

Timeline

1907 - First proposed by Clarence A. Chant
1921 - Public lecture introduces Dr. Chant to David Dunlap
1924 - David Dunlap dies at 61
1926 - Jessie Dunlap agrees to continue the observatory project
1930 - Final approval and project announcement
1933 - 74" mirror poured at Corning Glass Works
Telescope housing arrives in Canada for assembly
May 31, 1935 - Official Opening - DDO becomes world's second-largest telescope in operation
1935 - Dr. Helen Hogg joins DDO staff and begins internationally renowned research on globular star clusters; takes over 2000 images and discovers hundreds of variables stars that she discusses in over 200 publications
1951 - 15 cm Cooke refractor originally used at U of Toronto's downtown campus for the 1882 transit of Venus moved into the north dome of the DDO Administration Building. (Telescope donated to the National Science Museum in 1984.)
1953 - Dr. Don MacRae begins working for DDO and over next ten years constructs several radio telescopes at the Observatory and an 18 metre telescope in Algonquin Park
1958 - Dr. Sidney van den Bergh joins the DDO and devises a new classification system for galaxies using the Observatory's copy of the Palomar Sky Atlas; he goes on to become one of the giants in the study of galaxies
1970 - University of Toronto Southern Observatory (UTSO) begins operating at Las Campanas Observatory in Chile with instrumentation and operational support provided by the DDO. Dr. R. F. Garrison uses UTSO and DDO telescopes to establish himself as the world's foremost expert in stellar classification
1971 - Dr. Tom Bolton uses DDO 74" to confirm the existence of black holes
1995 - Town of Richmond Hill passes a landmark By-law to Regulate Light Pollution modelled after the efforts of Prof. Bolton during the preceding 25 years.
2007 - University of Toronto announces intention to close DDO in favour of Dunlap Institute
2008 - Property purchased by Metrus Development Inc, which advertises for an astronomy club to operate the observatory and telescope
2009 - Royal Astronomical Society of Canada, Toronto Centre, puts forward a proposal to operate the Observatory and telescope for education, public outreach programs, and astronomical research collaborations
July 2009 - David Dunlap Observatory reopens for public viewing nights and welcomes more than 1700 visitors in its first season of operation