Image of installation of a telescope frame in one of the telescope domes at the Rothney Astrophysical Observatory at Priddis.

Our History


Alan Clark was assigned the task of designing an observatory to support the new astronomy undergraduate program. This led directly to the generous offer of a quarter-section of land by Sandy Cross, a prominent rancher and long-time citizen with deep connections to the early history of Calgary. The adopted name of the resulting observatory incorporates the family name of Rothney in recognition of this initial gift.


Alan Clark and Gene Milone made the first astronomical observations on the new site by establishing the N-S line for the piers of the 16-inch telescope. This telescope was subsequently installed into the dome and a classroom was placed next to a multi-pillar terrace for student observing.


The Rothney Astrophysical Observatory was inaugurated on Jan. 7, 1972 with a dedication ceremony on site. Dr. Margaret Burbidge, director of the Royal Greenwich Observatory, attended and unveiled a sundial to mark the official opening. At that time, the observatory consisted of a joined pair of trailers for a classroom and office, a Minnaert observing terrace and, thanks to provincial matching funds, a 41-centimetre telescope and dome for astronomical research. Clark and Milone became responsible for operations.

Image of the 0.4 metre Clarke-Milone Telescope and the dome that houses it at the University of Calgary's Rothney Astrophysical Observatory located at Priddis, Alberta in 1972.


The National Research Council of Canada decided to finance the construction of a new facility. The facility would house a one-and-a-half metre telescope capable of operating in the infrared range. Alexander Rothney Cross signed on to the project by making another donation. The Canadian Forces Base Cold Lake also provided a gift: a Baker-Nunn camera that the armed forces had used to track satellites in the sky.


The one-and-a-half metre telescope was operational. The physics department changed its name to the Department of Physics and Astronomy. Most of the research work focused on the study of stars, x-ray sources, possible black holes and planetary nebulas. The telescope was still equipped with a metal mirror, and its optical qualities were considered less than optimal at that time. The decision was made to replace it with a new mirror.


A new mirror was delivered to the observatory. Once again, Alexander Rothney Cross contributed to the project. Construction was completed by the Department of Physics and Astronomy workshop.

Image of dignitaries inside the telescope dome while attending the opening of the University of Calgary Astrophysical Observatory in Priddis in 1971.


The telescope became operational. Alan Clark formally retired in 1996, but continued his involvement with the RAO by leading the IRT upgrade to accommodate the new high quality 1.8-m glass mirror.


The telescope was baptized as the Alexander Rothney Cross Telescope. The new telescope is used to observe gravitational lenses, asteroids, comets and variable stars. It is also used in the search for planets outside our solar system.


The RAO was awarded a Research Capacity Upgrade grant, of which $175,000 was from the Alberta Strategic Research Investments Program (ISRIP). The upgrades occurred over the period  2002-2005 and included to further automate the IRT. Renamed the Alexander R. Cross Telescope or ARCT after the optical quality 1.8-m mirror was installed. The upgrade also included a project to digitize the 40 cm telescope for remote operation, and remount the Baker-Nunn satellite tracking camera transforming it into the RAO Patrol Camera



Dr. Milone received approximately $400,000 from the Government of Alberta, the University of Calgary and private donors to build the interpretive centre. The initial open houses were held synchronously with the University of Calgary's Open Houses. The first regular RAO open house program was instituted in 1995, with seasonal monthly open houses at the RAO.  The subsequent successful Visitors' Centre grant was awarded on the strength and success of that program and came to fruition nearly a decade later.

Construction of telescope dome in 1971.

Image of a crane lowering a piece of a telescope frame into the open door of a telescope dome at the Rothney Astrophysical Observatory at Priddis in 1971.


The Department of Geology and Geophysics developed a direct, high speed, line-of-sight data link to dedicated servers on campus to permit both reliable and constant data transmission from the seismometer array. This development permits remote and robotic telescope operations.


The interpretive centre opened to the public. Public outreach and the open house program grew to include school and youth programs. Thousands of people visited the observatory annually. The Interpretive Centre developed as a hub for astronomy education.


The interim director, Rene Plume, stepped down and Phil Langill took the helm as the director of the observatory. The role and purpose of the observatory transformed with public programming and outreach activities. These new initiatives continued the tradition of the Rothney Astrophysical Observatory as an educational institution.


The Rothney Astrophysical Observatory received an ASTech award for Excellence In Science and Technology Public Awareness. We continue towards excellence with the valued feedback of teachers, students and all those who visit the observatory.


Rob Cardinal was looking for an asteroid using the Baker-Nunn telescope, but ended up finding a comet. This was the first comet discovered at the Rothney Astrophysical Observatory and only the second Canadian discovery of a comet, using a Canadian telescope, in nearly a decade. Rob discovered a second comet in 2010.


The Canadian Space Agency launched the CAScade, Smallsat and IOnospheric Polar Explorer also known as CASSIOPE. The satellite soars through the Earth's aurora and space weather collecting data, which is studied by the observatory’s scientists.


Aerial shot of the RAO

RAO Aerial View-JAN 2019

Image of telescopes University of Calgary's Rothney Astrophysical Observatory located at Priddis, Alberta in 1972.
Image of the Rothney Astrophysical Observatory at Priddis, Alberta in 1994.

RAO Circa 1994