Introduction

In this section we will discuss about the formation of the 'dirty beam' and the 'dirty map' from the visibilities obtained. Dirty beam is the Fourier transform of the $uv$-tracks for an observation. The dirty map is the convolution of the true brightness distribution with the dirty beam (see section 3.3.2.2). Also we will discuss about the image reconstruction from the dirty map, a process called deconvolution. We will also discuss the deconvolution algorithm called CLEAN, which is widely used for this purpose.

In the last part we would actually discuss the actual data reduction procedure as followed in the AIPS task IMAGR for obtaining the image of the source. We will also discuss the self-calibration technique to obtain the better quality image.