qimager.filter - Function

Apply additional weighting by filtering (u-v taper)

Synopsis filter(type, bmaj, bmin, bpa, async)

Description Apply visibility tapering to emphasize certain scale structures. The imaging tapers are applied to a Table column called IMAGING_WEIGHT, which may be plotted using plotweights. In addition, this column may be accessed directly using either the table or ms modules. Note that the taper is multiplicative and so the weights must be calculated first using weight. The points are not flagged!

Note that the scale size to be emphasized is given in the image plane as the parameters of the corresponding Gaussian. Note also use of this function provides an optimum detection for the given scale size, which is not the same as requiring that the resulting dirty beam have the specified Gaussian fit. The resultant fitted beam size will very roughly be the quadratic sum of the original beam and the specified beam. If you wish to obtain a specified beam, then the best approach is to perform this calculation and check the value obtained using qimager.fitpsf.

Arguments

`type`	Type of filtering or u-v tapering
	`Allowed:`	`String`
	`Default:`	`gaussian`
`bmaj`	Major axis of filter
	`Allowed:`	`Quantity`
	`Default:`	`'0rad'`
`bmin`	Minor axis of filter
	`Allowed:`	`Quantiy`
	`Default:`	`'0rad'`
`bpa`	Position angle of filter
	`Allowed:`	`Quantity`
	`Default:`	`'0deg'`
`async`	Run asynchronously in the background
	`Allowed:`	`Bool`
	`Default:`	`!dowait`

Returns Bool

Example

imgr.weight('uniform')
imgr.filter(type='gaussian', bmaj='2.3arcsec', bmin='1.67arcsec',
bpa='-34.5deg')

Next: qimager.uvrange - Function Up: qimager - Tool Previous: qimager.sensitivity - Function Contents Index

	`Package`	`synthesis`
	`Module`	`qimager`
	`Tool`	`qimager`