imsizeshould be large enough to contain all emission in the main lobe of the primary beam (as Miriad only models the main lobe, making it larger has no beneficial effect). Table 21.2 gives these sizes as a function of frequency for the ATCA.
supgives the sidelobe suppression region, and is a way of setting uniform, super-uniform and sub-uniform weights. In mosaic mode, invert's default is to suppress the sidelobes in a region the size of each sub-image. However suppressing sidelobes in an individual sub-images is not the same as suppressing them in the linear mosaic of the sub-images. This is because the linear mosaicing process weights down sidelobes some distance from the pointing centre. In mosaicing, minimum sidelobes will be achieved by setting sup equal to about twice the pointing separation (which should be about the side of the primary beam FWHM).
As always, best point-source sensitivity results by setting sup equal to 0.
|vis=lmc.uv||The input multi-pointing dataset.|
|options=mosaic,double||Use mosaic mode and make large beam.|
|offset||Usually can leave blank.|
|map=lmc.map||Output image name.|
|beam=lmc.beam||Output beam name.|
|cell=||Set cell size.|
|imsize=||Set output image size.|
|sup=2000||Set to approximately twice the pointing separation for|
|minimum sidelobes, or|
|sup=0||set to zero for best point-source sensitivity.|