View source for Milestone-Proposal:First Radio Astronomical Observations Using VLBI, 1967

{{Proposal|a1=First Radio Astronomical Observations Using VLBI, 1967|a2a=Dominion Radio Astrophysical Observatory, 25 km from Penticton, British Columbia, Canada.|a2b=Vancouver|a3=1967|a4=From its Canadian beginnings, VLBI has become an important technique for both radio astronomy and geodesy. It has been the central theme of over 3,500 papers in the scientific literature over the ten-year period 1999 to 2008, and the flow continues unabated.
VLBI provides better angular resolution than any optical telescope and can reveal details within some of the most distant objects detectable. Astronomers use VLBI to provide crucial tests of General Relativity, to demonstrate definitively the existence of black holes in galaxy cores, to test the fundamentals of high energy physics, and to look back to the early Universe. 
VLBI techniques also permit the position of objects on Earth and in the solar system to be measured with millimetre accuracy with respect to the ultimate reference frame, distant quasars. Such techniques are now routinely used: (1) to precisely track spacecraft on voyages to the planets and (2) to provide the basis for precise geodetic surveying including important studies of the movement of crustal plates, earthquake prediction and Earth rotation. See, for example,
J. L. Yen, P. Leone, G. A. Watson, J. K. Zao, J. Popelar, W. T. Petrachenko, G. Feil, W. H. Cannon, P. Mathieu, P. Newby, H. Tan, R. D. Wietfeldt, and J. A. Galt, '"The Canadian geophysical long baseline interferometer," Radio Science, vol. 26, no. 1, pp. 89-99, Jan.-Feb. 1991.
In the late 1970s the community of Canadian VLBI scientists developed a new concept, an array of large radio telescopes spread across the entire breadth of Canada working together, using VLBI techniques to form one giant imaging telescope, the Canadian Long Baseline Array. The project fell victim to a barren funding climate for science in Canada in the 1980s but the concept was used by US scientists to build the Very Long Baseline Array (the VLBA) across that country. The VLBA has been a scientific success story since its completion in 1993.

VLBI research continued with the DRAO 26-m Telescope until 1988. In 1990 DRAO scientists and engineers became involved with the first extension of VLBI techniques into Earth orbit. The DRAO team designed and built a forefront correlator, a special-purpose digital processor that combined signals from a Japanese space telescope, VSOP, with ground based radiotelescopes around the world. VSOP was launched in 1997 and operated with superb effectiveness until 2003, achieving many world firsts.|a5=Short-baseline interferometry had been used in radio astronomy for high-resolution imaging since the 1940’s.  Cables or (sometimes) radio links were used to connect two or more radio antennas to signal processing equipment.  The distance or baseline between pairs of antennas in such interferometers was initially small but gradually became larger over time. It soon became clear that important astrophysical questions could be answered only by building interferometers with baselines greater than any cable or radio link could span. The proposed IEEE Milestone will recognize the first successful radioastronomical observation made using such techniques.|a6=The principal technical challenge was to establish two independent receiver systems with individual clocks and recording devices that were sufficiently stable to maintain coherence over periods of many minutes and sufficiently sensitive to detect the very weak radio astronomical signals.

Great ingenuity was applied to operating within a limited budget and adapting existing equipment to the task. For example, the first VLBI observations were collected using surplus video recorders that had been purchased from the Canadian Broadcasting Corporation.|a7=The Dominion Radio Astrophysical Observatory (DRAO) is a National Facility for astronomy operated by the National Research Council Canada. It is operated to support the research of the Canadian astronomy community, mostly consisting of researchers in universities. 
The plaque will be installed on the base of the DRAO 26-m radiotelescope that was used as the western site of the first successful VLBI radio astronomical observations in April 1967 observations. This location will be readily accessible to the several thousand members of the general public that visit the Observatory site each year. 
For related background, see
http://www.nrc-cnrc.gc.ca/eng/facilities/hia/radio-astrophysical.html

http://www.ieee.ca/millennium/drao/DRAO_about.html|a8=Yes|a9=The site is accessible to the public seven days a week from Easter to Thanksgiving and five days a week through the winter. When staff are not present, the DRAO site is secured by electronically operated access gates and a security system. 

Observatory scientists typically give tours to 1000 school students throughout the year. A professional guide typically gives weekend tours to 5000 visitors per year. Casual self-guided visitors to the site typically number 5000 each year.  The Observatory holds an Open House every September that typically attracts over 1000 visitors each year.|a10=National Research Council Canada (NRC)|a11=Yes|a12=IEEE Vancouver Section, Dave Michelson, Chair, dmichelson@ieee.org|a13name=Dave Michelson|a13section=Vancouver|a13position=Chair|a13email=dmichelson@ieee.org|a14name=Dave Michelson|a14ou=Vancouver Section|a14position=Chair|a14email=dmichelson@ieee.org|a15Aname=Dave Michelson|a15Aemail=dmichelson@ieee.org|a15Aname2=Tom Landecker|a15Aemail2=Tom.Landecker@nrc-cnrc.gc.ca|a15Bname=Dave Michelson|a15Bemail=dmichelson@ieee.org|a15Bname2=Tom Landecker|a15Bemail2=Tom.Landecker@nrc-cnrc.gc.ca|a15Cname=Dave Michelson|a15Ctitle=Chair|a15Corg=IEEE Vancouver Section|a15Caddress=UBC Electrical and Computer Engineering, 2332 Main Mall, Vancouver, BC  V6T 1Z4|a15Cphone=604 822-3544|a15Cemail=dmichelson@ieee.org}}