Imaging Flanking Fields

The ability to image flanking fields will be introduced in CASA v. 3.0.0. For the purposes of this guide, flanking fields are the locations of neighboring radio sources that can contribute significant, confusing signal to your science target. The confusing signal is introduced through sidelobes, which are local maxima of the point response function, or beam.

To achieve the highest quality image of the science target, these neighboring radio sources must also be imaged and deconvolved to reduce the sidelobe contribution. One approach is to image a very large field around your science target; however, long baseline configurations require small pixels to sample the synthesized beam, and the number of pixels required to map the primary beam becomes inconveniently large. To illustrate, the following table lists the image sizes required to map the VLA primary beam at observing frequency 1.4 GHz and for the four primary array configurations.