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Imaging Techniques: Limitations to the Quality of Images

Published online by Cambridge University Press:  19 July 2016

T. J. Cornwell
T. J. Cornwell*
Affiliation:
National Radio Astronomy Observatory, * Socorro, New Mexico, 87801

Extract

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Our ideas of how to image objects have progressed by leaps and bounds in the last twenty to thirty years. We now have a sophisticated understanding of many clever and subtle approaches to imaging. There are a few outstanding contributions which have provoked flurries of development and acheivement in many different areas: top of my list would be the principle of aperture synthesis, Jennison's closure phase, Högbom's CLEAN algorithm and Labeyrie's speckles. In addition, we have benefited tremendously from developments in computing hardware, software and algorithms (the most spectacular being the Cooley-Tukey Fast Fourier Transform). Each one of these contributions did not so much spur development in existing areas as open up entirely new vistas of possibilities. For example, Jennison's closure phase is rarely directly used by radio-interferometrists now but it did show, particularly when developed in VLBI, that imaging in the presence of severe phase errors is possible. This success then encouraged the two separate developments. First in the more flexible selfcalibration routines in which closure is implicit and, second, in pushing imaging interferometric arrays to shorter and shorter wavelengths, now ending up in the infra-red and optical regimes. Following on from these great works, many people have made lesser but still vital contributions. The example of speckle comes to mind as one where many people have had a hand in determining what is now standard technique.

Type
Transfer of Techniques
Information
Symposium - International Astronomical Union , Volume 158: Very High Angular Resolution Imaging , 1994 , pp. 37 - 45
Copyright
Copyright © Kluwer 1994 

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