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David Dunlap Observatory

By Craig Lee
DDO Administration Building Historical Tour                                                                                    When the observatory in downtown Toronto could no longer function due to light pollution, the University of Toronto identified a Richmond Hill farmstead as being suitable for a new astronomical facility. As a result, Jessie Donalda Dunlap purchased the property and donated it to the University as a memorial to her husband, David Alexander Dunlap, who was an avid astronomer. The University constructed the Observatory on the site. It included a dome, housing a 74-inch (1.88m) reflector telescope, and an Administration Building, with three smaller telescope domes. When construction was complete in 1935, the main telescope was the second largest in the world and the largest in Canada. From 1935 to 2007, the Observatory was at the forefront of Canadian astronomical research. Achievements at the site included advances in radio astronomy and the first direct evidence that Cygnus X-1 was a black hole. In June 2008, the University sold the property to a developer. In 2012 the Town of Richmond Hill (through an agreement with the Ontario Municipal Board) bought half of the D.D.O. Property. This land was to be used as  a public park and cultural heritage site.

Wednesday May 15, 2019

10:00 a.m.

123 Hillsview Dr.,
Richmond Hill  

Hillsview Dr. is west off Bayview Ave and is one street south of Weldrick Rd. E. (The observatory is not accessible from Yonge St.)

$8.00 per person

Please note that this site is currently not accessible.
This is a Historic Tour of the Administration Building and a visit to the Observatory to see the telescope.

You will not be “seeing through” the telescope on this tour. If you are looking for an opportunity to see the telescope in use and to see through the telescope,visit the town website to see other tours which are offered to the public.
Order by April 10

Send your registration with a cheque made out to:
RTO/ERO District 34 to:

Craig Lee
21 Lippincott Court
Richmond Hill,
ON L4C 7M5

Acknowledgements will be emailed upon receiving the registration form.


To register, click here