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maxen

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NAME

maxen - Maximum Entropy deconvolution  

PERSON RESPONSIBLE

rjs  

CATEGORIES

deconvolution  

DESCRIPTION

MAXEN is a MIRIAD task which performs a maximum entropy deconvolution algorithm on a cube.  

PARAMETERS

map
The input dirty map, which should have units of Jy/beam. No default.
beam
The input dirty beam. No default
model
An initial estimate of the deconvolved image. For point sources, giving a good initial model may help convergence. In principle, this only helps convergence, but should not affect the final solution. The model could be the output from a previous run of MAXEN or any other deconvolution task. It must have flux units of Jy/pixel. The default is a flat estimate, with the correct flux.
default
The default image. This is the image that the final solution will tend towards. The final result will be influenced by this default if the constrains that the data put on the solution are weak. The default is a flat estimate, with the correct flux.
out
The name of the output map. The units of the output will be Jy/pixel. It can be input to RESTOR, MAXEN (as a model, to continue the deconvolution process), or to SELFCAL (for self-calibrating visibility data).
niters
The maximum number of iterations. The default is 20.
region
This specifies the region to be deconvolved. See the Users Manual for instructions on how to specify this. The default is the largest centered region that it is safe to deconvolve.
measure
The entropy measure to be used, either "gull" (-p*log(p/e)) or "cornwell" (-log(cosh(p)) -- also called the maximum emptyness criterion). The default is "gull".
tol
Tolerance of solution. There is no need to change this from the default of 0.01.
q
An estimate of the number of points per beam. MAXEN can usually come up with a pretty good, image dependent estimate.
rms
The rms noise, in Jy/beam, in the dirty map. No default. The convergence and behavior of MAXEN depends strongly on the value of this parameter.
flux
The flux of the source. If FLUX is given as a positive number, then the resultant image is constrained to have this flux. If FLUX is negative, then abs(FLUX) is used as an estimate of the source flux only and the actual flux is allowed to vary. If FLUX=0, then MAXEN makes a guess at the source flux. Default is FLUX=0, though you should give MAXEN more information if at all possible. On the other hand, a bad value here can cause MAXEN to blow up.
options
Task enrichment parameters. Several can be given, separated by commas. Minimum match is used. Possible values are:
  quiet      Do not give any messages during iterations. The default
             is to give a one line message at each iteration.
  verbose    Give lots of messages during the iterations. The default
             is to give a one line message at each iteration.
  asym       The beam is asymmetric. By default MAXEN assumes the
             beam has 180 degree rotation symmetry, which is the
             norm for beams in radio-astronomy.
  pad        Double the beam size by padding it with zeros. This
             will give better stability if you are daring enough
             to deconvolve more than the inner quarter of the dirty
             image.


 

Index

NAME
PERSON RESPONSIBLE
CATEGORIES
DESCRIPTION
PARAMETERS

This document was created by man2html, using the manual pages.
Time: 18:35:38 GMT, July 05, 2011