In 1956 the Dominion Astronomer, C. S. Beals, recommended that a radio observatory be built to study the interstellar medium (ISM) in our galaxy. A site survey was undertaken in 1957, and the White Lake Basin site was chosen. Construction began in 1958. The first telescope on site was the 26-m Telescope, completed in 1959, and still active today in gathering data for world-leading research. 

Since the official opening in 1960 DRAO has enjoyed 50 years of world-class astronomy and technology development in the White Lake Basin.

Astronomy

1960s: low-frequency arrays

In the 1960s the nature of quasars was still a subject of great debate. In order to better understand them, attempts were made around the world to characterize their radio spectrum. DRAO’s contribution was the constructions of large arrays working at the very low frequencies of 10 and 22MHz, at the time the largest radio telescopes in the world. This programme also discovered the existence of radio haloes around clusters of galaxies. Data from these telescopes remain today the best available at those frequencies. The 10-MHz Array is long gone, but the wooden poles of the 22-MHz Array continue to be a source of curiosity for visitors.

1967: the development of VLBI

Also in pursuit of understanding quasars, in 1967 researchers at NRC conducted the first successful trans-continental VLBI experiment, using the DRAO 26-m Telescope and the Algonquin Radio Observatory 46-m antenna in Ontario. This technique allowed an unprecedented look at the size of quasars, helping greatly in understanding their nature.

1970s – 1980s: the Synthesis Telescope

Planning for the DRAO Synthesis Telescope began in the late 1960s, and construction commenced in 1970, with the telescope entering operation in 1972. Initially having 2 antennas operating at 1420MHz, it made pioneering observations of the Galactic interstellar medium. A key technique was developed in 1977 that allowed, for the first time, the combination of data from single-antenna and synthesis telescopes. This was shown to be key in properly understanding the properties of extended radio sources, and is widely practised today. Around 1980 the telescope was expanded to 4 antennas, and through the 1980s additional capabilities were added, including a simultaneous 408MHz channel, and improved digital processing electronics. During this period DRAO established itself as a National Facility for radio astronomy.

1990s – 2000s: the CGPS era

The Canadian Galactic Plane Survey (CGPS) was conceived in the early 1990s to exploit a new upgrade of the Synthesis Telescope to have 7 antennas with dual polarization capability, and further improvements in digital processing electronics. An international consortium of 96 researchers, led from Canada, used the Synthesis Telescope from 1995–2009 to make the highest fidelity image of our Milky Way galaxy at centimetre wavelengths. The observations comprised both radio continuum and atomic hydrogen data from the DRAO Synthesis Telescope and the DRAO 26-m Telescope, along with carbon monoxide data – an important tracer of star formation – from another observatory. DRAO developed the special observing and data processing techniques required to obtain the high quality images of the Milky Way, which have seen praise from as “the best radio images ever made”. 

When DRAO embarked on the CGPS, survey science was niche endeavour, but today the main science drivers for new and planned telescopes rely heavily on survey science, and the techniques developed by DRAO are coming into widespread use in radio astronomy.

2010: GMIMS and beyond

DRAO researchers are now leading an international consortium that is employing telescopes Canada (the DRAO 26-m Telescope), Australia, Germany, and China to make all-sky surveys of the polarization of astronomical radio emission as a function of frequency. The Global Magneto-Ionic Medium Survey (GMIMS) will provide unprecedented information about the interstellar medium (ISM, which affects the polarization state of the radio waves as they pass through), and, ultimately, the source of the radio waves, in which electrons interact with magnetic fields. Those magnetic fields are among the most important but least understood constituents of the ISM, and are considered a key science driver for future telescope. GMIMS promises to provide valuable data on magnetic fields that will guide future work for many years.

Solar Radio Monitoring Programme

Since 1990 the Solar Radio Monitoring Programme has been based at DRAO. A continuation of a pioneering radio astronomy experiment begun by Arthur Covington in Ottawa in 1946, this programme makes accurately calibrated measurements of the solar radio flux on a daily basis, and disseminates this information internationally. The "10.7cm solar flux'' is widely used for "space weather'' applications by many agencies internationally (including NASA, NOAA, DOD), as well as power utilities, and satellite operators.

Technology Development

DRAO today has a strong Astronomy Technology Research Group that has achieved international renown in diverse areas such as digital signal processing, antenna design, and radio receivers.

Digital Signal Processing

DRAO is a world leader in the design and construction of digital systems for astronomy, from the first digital systems on the DRAO Synthesis Telescope to cutting-edge projects for observatories around the world. Some recent projects include:

• the Space-VLBI correlator, funded by the Canadian Space Agency, and used for the VLBI Space Observatory Programme (VSOP) run by the Japanese Institute for Space and Aeronautical Science (ISAS), combining data from ground-based radio-telescopes and the orbiting satellite radio-telescope HALCA.

• the ACSIS (Autocorrelation Spectrometer and Imaging System) correlator for the James Clerk Maxwell Telescope (JCMT) in Hawaii. This correlator has been an essential instrument for the JCMT over the past few years, most especially with its unique real-time data processing system.

• the patented Wideband Digital Architecture (WIDAR) design, used in the correlator system designed and assembled at DRAO for the Expanded Very Large Array (EVLA) in New Mexico, USA. This is currently the largest and most powerful digital correlator system in the world, with a performance speed equivalent to the fastest supercomputer systems in the world today. This $20M correlator system, funded by the Canadian government, is being commissioned currently at the EVLA, which is the largest radio telescope in the world.

• DRAO developed the concept for a real-time, very high-speed computer system for the adaptive optics systems required for the Thirty Metre Telescope (TMT), a 30-m diameter optical telescopes being developed by a US-led consortium that includes Canada. This system is essential for the TMT to attain the highest resolution capabilities of the telescope. This design study was awarded to DRAO in a competition involving some of the world largest aerospace technology companies.

Antenna Design

DRAO has designed and built low-cost, high performance radio antennas using the latest composite material techniques. This work led to the DRAO team winning the JEC Composites Asia International Award for Innovative Applications in Aerospace Composites in 2008, which has attracted widespread interest from the composites industry.

Such antennas are essential to the success of new projects that demand many (~1000) small-diameter radio-telescopes to make rapid images of the whole sky. These telescopes will be able to detect and image some of the weakest extended radio emission from the universe, and significantly advance our understanding of the Universe, and the origins of solar systems such as our own. This large-number, small-diameter telescope concept, too, originated at DRAO in the 1980s, and is now central to the design of new radio telescope facilities in the US, Australia, and South Africa, and is being advanced for the Square Kilometre Array, a global project that aims to build the world's largest radio telescope.

Radio Receivers

DRAO is a leader in the development of array receivers for radio telescopes. Such receivers are the equivalent to a digital camera on a radio telescope, being able to image multiple pieces of the sky simultaneously. To aid in this work, DRAO is also collaborating closely with university partners to develop sensitive amplifiers that will allow superior performance at ambient temperature, versus the expensive cooling systems currently required.