| 21st of February 2018 |
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| Potts Hill, from the CSIRO Radio Astronomy Image Archive |
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The image above, dating from January 1953, is taken from the CSIRO Radio Astronomy Image Archive.
The picture shows CSIRO staff working on a 36 ft (11 m) diameter antenna located at Potts Hill, Sydney.
Following the first detections in 1951 of radio emission from neutral hydrogen (HI) in the US and Netherlands,
this antenna was used as a transit instrument to map the distribution of HI in the Milky Way.
These observations, together with observations from Leiden, showed that the Milky Way is a spiral galaxy
with HI concentrated in near-circular orbits within the spiral arms (Oort et al. 1958).
The Potts Hill receiver hut, seen just behind the antenna is still standing and has recently been restored by the Sydney Water Board
(as will be shown in an ADAP in coming days). The CSIRO Radio Astronomy Image Archive includes over 22,000 digital images. Of these about 15,000 are historical images that were taken by professional CSIRO photographers between 1943 and 1996 and which have been digitised at high resolution. The archive can be accessed from the CASS headquarters in Marsfield, with a web interface expected to be available later this year.
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