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Paper: Discovering CO and Other Interstellar Molecules with the NRAO 36 Foot Antenna
Volume: 395, Frontiers of Astrophysics: A Celebration of NRAO's 50th Anniversary
Page: 183
Authors: Wilson, R.W.
Abstract: Bell Labs was an early developer of millimeter-wave technology. In the 60’s there was a big push to develop a millimeter wave long-distance communications system to do what ultimately fiber optics has accomplished. As part of this system, Charles Burrus at Crawford Hill developed millimeter-wave receivers by making Schottky-barrier diodes using modern photolithography. Arno Penzias and I recognized that these had a potential use in radio astronomy and with Ken Kellermann proposed to build a receiver with them for use on the then-new 36 foot antenna. Unfortunately this attempt was premature and not successful. In 1970 Arno, Keith Jefferts, and I—with much help from Sandy Weinreb—put together a spectral-line receiver. This was done with the hope of detecting rotational transitions of simple molecules in interstellar space. Since, at the time, only a few people (like Phil Solomon) had any idea that molecular clouds existed, we prepared to detect a weak signal. Our backup strategy, suggested by Pat Thaddeus, was to look for CN, which had been known to exist since the late 1930s. If neither line had been detected, we would have observed the H38α recombination line which is close in frequency to the CO J=1−0 line. As we all know now, however, the signal from carbon monoxide (and even its less abundant isotopes) was remarkably strong. Such measurements have since transformed our ideas of star formation.
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