Colloq Abstract -Ekers

Sep 1

11am Mountain

Ron Ekers  (CSIRO)

The history of the development of Aperture Synthesis in radio astronomy.

Abstract

One of the most important events in twentieth century astronomy was the birth of radio astronomy. For the first time ever astronomers were able to view the Universe in a region of the electromagnetic spectrum outside the narrow optical window. However the long radio wavelengths made it difficult to image the sky with sufficient angular resolution.  Structures were measured indirectly using interferometers and interferometer arrays.  X-ray crystallography played an important role in the early development of what became known as aperture synthesis and in 1974 Sir Martin Ryle received the Nobel prize for the invention and development of these radio-astronomical instruments.  
 
I will discuss the early instrumental developments, focussing on Cambridge (UK) and in Sydney (Australia), and include the methods used for computing the Fourier transforms.  I will than provide a brief overview of the refinements of this indirect imaging process such as deconvolution algorithms and adaptive calibration techniques which occurred in many countries.   I will also comment on the interactions between the groups involved, and between the astronomers, the crystallographers and the medical imaging practitioners.