Astrolabe; A. Danjon; 2014.5398.9



About this object

Impersonal Astrolabe; manufactured by Optique et Precision de Levallois (OPL), France, circa 1955. Used by a team at the Seismological Observatory, DSIR, led by R C Hayes during the International Geophysical Year (1957-1958) as part of a worldwide programme of observations determining the position of Earth's land masses in relation to each other.

The astrolabe (purchased specifically for the programme, and identical to those used for the same purpose at observatories worldwide) determines the instant at which a set of about 24 stars reach the same very precisely defined altitude. If the positions of the stars are known, calculations allow the longitude, the latitude, and the clock error to be worked out. Two or three groups of stars were observed every fine night, each group taking about two hours to observe. The astrolabe was housed in the astrolabe dome near the Dominion Observatory, this structure is still in existence. Instruments used in conjunction with the astrolabe were designed and built on site at the Seismological Observatory. All in all there were many months of preparation, eighteen months of observing, followed by at least a year of processing results for sending to Paris.

Right through the IGY, and in spite of the colossal amount of extra work it brought, the seismological work of the Observatory and the normal time service were carried on without additional help, except for the observers and recorders who helped with the astrolabe programme.

R C Hayes retired shortly after in 1960.

Sourced from 'In Spite of his Time: A Biography of R C Hayes', by Margaret Hayes, 1987.


A. Danjon

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Astronomical Instruments

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