Radio Observatory at Maipú Completes Mission, Closes Doors

Abstract

After 40 years of operation, the Radio Observatory of the University of Chile (ROM), located at Maipú, has closed down. The ROM came to life in 1959, 27 years after Karl Jansky’s momentous discovery of cosmic radio waves. The facility was the result of two cooperative programs of the University of Chile, one with the department of terrestrial magnetism (DTM) of the Carnegie Institution of Washington and the other with the University of Florida in Gainesville. These efforts were initiated and encouraged by the late Federico Rutllant, director of the National Astronomical Observatory of the University of Chile, who wanted to have the university involved in radio astronomy. Rutllant’s more ambitious interests led to the installation of large international observatories in northern Chile. At the DTM he met Merle A. Tuve, who was enthusiastic about developing radio astronomy in South America. In Gainesville, Rutllant met Alex G. Smith, who wanted to observe Jupiter’s decametric emission from the Southern Hemisphere.As a student I tested the prospective sites. After Maipú was selected, I worked with the DTM in designing and building a 1200-meter-long, 16-element interferometer to observe the Sun at 175 MHz. John W. Firor and Bernard F. Burke, then at the DTM, helped me with the fundamentals of interferometry. Jorge May, also a student, worked with Thomas D. Carr on different types of antennas to observe Jupiter. The first successful observation was made on 25 November 1959, when the interferometer recorded a strong solar storm. As far as we know, the ROM was the first operating radio observatory in Latin America. It worked at very low frequencies and carried out observations of the Sun, pulsars, SN1987A, the Magellanic Clouds, and so forth. However, its most successful tasks were the decametric observations of Jupiter that spanned two Jovian years, and the 45-MHz continuum survey of the southern sky. The latter survey was done with a large filled array that worked as a transit instrument; because of problems inherent in very low-frequency observations, the southern survey took 15 years to complete. The observations were combined later with others made from the Northern Hemisphere with a similar antenna, resulting in an all-sky survey at 45 MHz.The ROM made significant contributions to teaching. A number of electrical engineering students obtained their degrees under the guidance of engineer Juan Aparici, who was responsible for most of the electronic design and construction. Also, several students received MS degrees in astronomy.The ROM became a solid research center, establishing cooperative programs with international institutions. The first was in the mid-1980s with Columbia University in the US, through the installation and use of a 1.2-meter dish, built to observe molecular line emission in the mm-wavelength range, at Cerro Tololo InterAmerican Observatory. Carbon monoxide is important in the interstellar medium because it radiates a strong line in the 1–0 transition and is a good tracer of molecular hydrogen, which does not emit radio waves. The main goal, successfully accomplished, was to make a survey of the southern Milky Way in that transition. This pioneer project opened the rich field of mm-wave spectroscopy. Part of the ROM’s legacy is a new generation of Chilean radioastronomers who are involved in important cooperative programs with the US, Japan, and several European countries.The ROM had scant funding, but it received equipment donations from the University of Florida, the NASA satellite tracking station near Santiago, and the European Southern Observatory. Many people associated with the ROM deserve mention here, but space limitations prevent it. Credit for keeping the ROM running belongs to Jorge May.So, with the great satisfaction of knowing that the ROM achieved its primary goal, yet with deep sadness, we have turned the power off at the Maipú Radio Observatory. The radio astronomy observatory at Maipú, Chile, in October 1959. In the left foreground is a Yagi radio antenna of the solar interferometer; on the right is the inclined plane of another antenna. In the middle, near the building, the tall V-shaped structures make up the corner reflector. Both the inclined-plane antenna and the corner reflector were used primarily for observations of Jupiter.PPT|High resolution© 2001 American Institute of Physics.