Ashok K. Singal
Astronomy & Astrophysics Division, Physical Research
Laboratory, Ahmedabad, 380 009, India
Abstract. Some basic concepts in use for making astronomical
observations
at radio wavelengths are introduced. In particular the importance of
phase information for imaging in radio astronomy is highlighted. Using simple
examples
it is demonstrated how phase information is much more essential than
that even
of amplitude for an image reconstruction from its Fourier components.
Keywords: Techniques: image processing - radio continuum: galaxies - (galaxies:) quasars: individual:1432+158