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A complex international structure exists for the administration of the radio spectrum, now widely viewed as an increasingly valuable natural resource. Radio astronomy was first officially recognized as a radio communications service at the World Administrative Radio Conference of 1959. At that time the IAU, URSI and COSPAR set up under ICSU the Inter-Union Commission for the Allocation of Frequencies for Radio Astronomy and Space Science (IUCAF) to represent scientific usage of the spectrum. Radio astronomers work through their national agencies or IUCAF to get their concerns considered by the International Telecommunications Union (ITU), or included on the agenda of a World Radio Conference. In addition to IUCAF, National and Regional committees such as the US Committee on Radio Frequencies (CORF) and the European Committee on Radio Astronomy Frequencies (CRAF) facilitate a united participation by radio astronomers.
It is essential that the unique requirements of the passive services be clearly documented and readily accessible to professional spectrum managers more attuned to the requirements of government and commercial transmitting services. The ITU Radiocommunications Sector is supporting this effort by the publication of ``Handbook on Radio Astronomy''. This document, prepared by an international team of radio astronomers experienced in frequency management, describes the characteristics of the radio astronomy service, the preferred frequency bands for radio astronomy use, and the extreme sensitivity and resulting vulnerability of radio astronomy observations to interference. It defines sharing criteria, harmful interference limits, and the threat of unwanted emissions from broad band (spread spectrum) modulation.
Copies of the ITU ``Handbook on Radio Astronomy'' should be in every engineering and astronomy library, and the material it provides can usefully be included in college and graduate level courses. The Handbook is available in both English and Spanish from the ITU in Geneva.
