RADIO ASTRONOMY AT CORNELL UNIVERSITY: THE EARLY YEARS, 1946 TO 1962

Abstract

In 1946 the Microwave Astronomy Project was initiated by the School of Electrical Engineering at Cornell University, the first university in the United States to enter the new field of radio astronomy as it was later called. While the Engineering School's Director, Charles Burrows, led the project, the initiative came from Charles Seeger, a faculty member in Electrical Engineering, and two instructors in the Department of Astronomy, Ralph Williamson and Donald McRae, both of whom left Cornell in 1946. With funding from the U.S. Office of Naval Research, two World War II SCR-268 radar systems, which operated at 200 MHz, were acquired and plans made to construct a 6-m diameter parabolic antenna that would operate at frequencies up to 10 GHz. A site was chosen about 8 km from the Cornell university campus. The parabolic antenna was completed in 1948 although using a borrowed 5-m reflector that, initially, could only operate up to 200 MHz. Its completion in October was in conjunction with the first conference on radio astronomy held in the United States, which attracted considerable publicity for this new research field. Initial observations of the Sun were made in June 1948 using the two receiving 4 × 6 dipole arrays from the SCR-268 radars mounted on the elevation arm of one of the radar systems. This was followed by routine solar observations from July 1948 to December 1949. Initial results were published by Martha Stahr, Assistant Professor of Astronomy at Cornell. During the summer and fall of 1948 two more observational programs were started. Charles Seeger and Ralph Williamson determined the direction of the radio pole of our Galaxy using the SCR-268 mattress array and Seeger did extensive observations of the strong variable source Cygnus A using, initially, the mattress array and, later, the 5-m antenna. In late 1949 Leif Owren joined the project to pursue a doctoral degree based on solar radio observations. These started in mid-1950 and continued until December 1952, initially with the 5-m antenna and, later, with the mattress array while the 5-m antenna was being resurfaced to allow operation at1,420 MHz. Owren also built a two element interferometer to study the relationship between solar radio bursts andoptically observed plages and sunspots. Charles Seeger left Cornell in 1950 and Owren in 1952, leaving noastronomers with a strong interest in the radio astronomy program until Marshall Cohen joined the faculty in 1954.Cohen initiated studies of the polarization properties of solar radio emission with the 5-m antenna that continued intothe 1960s both at the original site and, after 1962, at a new site south-east of Cornell University in the town of Danby.Only the 5-m antenna was moved to this site and it was decommissioned when the radio astronomy technical group,which by this time was primarily working in support of the newly built Arecibo 305-m telescope, was again moved to asite closer to Cornell University.