Bandwidth Smearing

The effect of a finite bandwidth of the observation is to reduce the amplitude of the visibility by a factor given by,

$$\rm {sin(\pi l \Delta\nu / \nu_{0} \theta)/(\pi l \Delta\nu / \nu_{0}\theta)},$$ (3..4)

where, $\theta$ is the angular size of the synthesized beam, $\nu_{0}$ is the center of the observing band, $l$ is location of the point source relative to the field center and $\Delta \nu$ is the bandwidth of the signal being recorded.

The effect of the bandwidth smearing can be reduced if the RF band is split into frequency channels with smaller channel widths and $u$ & $v$ computed for each measurement wile gridding. This effect can be important at 235 MHz for bandwidths greater than 1$-$2 MHz.