On a 230-metre mountain just north of Victoria, the Dominion Astrophysical Observatory (DAO)’s 1.8 metre reflecting telescope has probed the night skies for 92 years. It’s apt now that Parks Canada should designate the observatory as a national historic site to recognize its importance to Canadian astronomy’s development.

“The DAO and its early staff helped bring Canadian astronomy to an extremely high level of international regard,” says its director, Dr. Jim Hesser. He adds that the Parks Canada designation allows NRC to maintain the Observatory as a working scientific instrument while respecting its historic architecture.
The 1.8 metre diameter Belgian-cast glass primary mirror that first caught starlight on May 6, 1918, was replaced in the mid-1970s with one that is unaffected by temperature changes. The original spectrograph — an instrument that breaks down a star’s light to determine its chemical composition — has been upgraded many times. Digital cameras and a new polarimeter developed by the NRC Herzberg Institute of Astrophysics (NRC-HIA) have taken advantage of emerging technologies. But the building, Observatory dome and nine-metre steel telescope frame remain original.According to Dr. Hesser, the Observatory building’s design may still say “1918” to casual eyes, but nearly a century of accumulated upgrades make the telescope 10,000 times more sensitive than it was when new — and thus capable of contributing to 21st century astronomical research.
“It’s pretty remarkable that after all these years, we’re still using much of the same equipment,” says Dr. David Bohlender, the NRC-HIA research officer in charge of the telescope. “We have plans to continue to enhance its operation over the coming years and look forward to carrying on the reputation of the Observatory.”
While much of Canadian astronomy’s focus has shifted toward larger and newer facilities such as the Canada-France-Hawaii and Geminitelescopes, such upgrades keep the DAO “in the picture.” Dr. Bohlender says the Observatory’s main strengths include hosting long-term observing programs, providing long blocks of uninterrupted observing time, and training next-generation astronomers for their scientific careers.Dr. Hesser adds that the telescope’s original tracking mechanism — a “very beautiful” gravity-driven brass clock drive — remained so accurate that it was only disconnected in the late 1980s, in favour of a new computer system that automates telescope guiding and improves the accuracy of its pointing.
For more information, check out the official press release from the National Research Council.


eNews date: 
Friday, July 29, 2011