American Scientist

To the Editors:

The Spotlight Q&A by Brian Malow entitled “First Person: Yuri Kovalev” in the May–June issue gave an interesting account of the research with the Very Long Baseline Interferometry (VLBI) satellite RadioAstron.

However, I wish to correct one factual error in the remarks by Dr. Kovalev concerning the history of ground-based VLBI. The statement, “It [VLBI] was first successfully implemented by American scientists, which is often the case, and was one of the first intercontinental experiments between the United States and Russia,” is incorrect.

The first fully successful VLBI experiment was conducted by a group of Canadian radio astronomers in early 1967, and the results were published in consecutive papers in Science and Nature (both by N. W. Broten and colleagues). The experiment included stations at the Algonquin Radio Observatory near Ottawa, Ontario, and the Dominion Radio Astrophysical Observatory near Penticton, British Columbia, a baseline of 3,074 kilometers.

At the time there was an intense but friendly rivalry between Canadian and American groups, and the American success followed quickly, also in 1967. The Canadian first was at least partially attributable to the acquisition of three analog video tape recorders used in the television broadcast industry by the Canadian Broadcasting Corporation (CBC). It was fortuitous that the CBC was converting to color broadcasting at the time and no longer needed their black-and-white recorders. These recorders had a much wider bandwidth and longer recording time than the American system (which was based on digital instrumentation recorders), thus permitting a higher sensitivity to the signals from quasars such as 3C 273.

A second point is that the above quotation appears to indicate that the VLBI experiments between the United States and Russia were part of the initial successes in 1967. However, the U.S.-Russia experiments were conducted later, beginning around 1969.

As Dr. Kovalev indicates, they were a remarkable achievement given that they occurred during the depths of the Cold War period. It is indeed gratifying that nations can sometimes find ways around even hostile political differences to cooperate scientifically for the betterment of humankind as a whole.

E. R. Seaquist
University of Toronto (Emeritus)
Toronto, Canada