feather_pg.feather_pg_ Class Reference

List of all members.

Public Member Functions
def	__init__
def	__call__
Private Attributes
	__bases__
	__doc__
Static Private Attributes
string	__name__

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Detailed Description

Definition at line 18 of file feather_pg.py.

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Constructor & Destructor Documentation

def feather_pg.feather_pg_.__init__

(

self

)

Definition at line 21 of file feather_pg.py.

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Member Function Documentation

def feather_pg.feather_pg_.__call__	(		self,
			imagename = None,
			highres = None,
			lowres = None,
			sdfactor = None,
			effdishdiam = None,
			showplot = None,
			async = None
	)

Combine two images using their Fourier transforms

Feathering is a simple method for combining two images with different 
spatial resolution.  The processing steps are:

       1. Regrid the low-resolution image to a temporary copy matching the
   resolution of the high-resolution image,
       2. Transform each image to the spatial-frequency plane (gridded).
       3. Scale the low-resolution image (uv-grid) by the ratio of the
   volumes of the two 'clean beams' (high-res/low-res). 
       4. Add to this, the uv-grid of the high-resolution image, scaled by
   (1-wt) where 'wt' is the Fourier transform of the 'clean beam'
   defined in the low-resolution image.
       5. Transform back to the image plane.

Both input images must have a well-defined beam shape for this task to work. 
This could be a 'clean beam' for interferometric images, and a 'primary-beam' 
for a single-dish image. 

The two images must also have the same flux density normalization scale.

Keyword arguments:
imagename -- Name of output feathered image
default: none; example: imagename='orion_combined.im'
highres -- Name of high resolution (interferometer) image
default: none; example: highres='orion_vla.im'
     This image is often a clean image obtained from synthesis
observations.
lowres -- Name of low resolution (single dish) image
default: none; example: lowres='orion_gbt.im'
     This image is often a image from a single-dish observations
or a clean image obtained from lower resolution synthesis
observations.
 sdfactor -- value by which to scale the Single Dish image. Default is 1.0
         Basically modifying the flux scale of the SD image
 effdishdiam -- New effective SingleDish diameter to use in m. Obviously one can only reduce the dish effective dish diameter in feathering. Default -1.0 means leave as is.
 showplot -- If True will plot the cuts across the feathring function


Comments:

This task can be used as one method of combining single-dish and 
interferometric images after they have been separately made.

The clean task allows another method of combining single-dish and
interferometric data. The single-dish image can be used as a starting 
model for the interferometric image-reconstruction. If there is
some overlap between the spatial-frequencies contained in the 
single-dish image and the interferometer sampling function, then,
such a starting model will help constrain the solutions on the 
short-baselines of the interferometric data.

Definition at line 26 of file feather_pg.py.

References vla_uvfits_line_sf.verify.

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Member Data Documentation

feather_pg.feather_pg_.__bases__ [private]

Definition at line 22 of file feather_pg.py.

feather_pg.feather_pg_.__doc__ [private]

Definition at line 23 of file feather_pg.py.

string feather_pg.feather_pg_.__name__ [static, private]

Definition at line 19 of file feather_pg.py.

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The documentation for this class was generated from the following file:

• feather_pg.py