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tvcln

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NAME

tvcln - Clark/Steer CLEAN with display of intermediates  

PERSON RESPONSIBLE

rjs  

CATEGORIES

deconvolution  

DESCRIPTION

TVCLN is a MIRIAD task, which performs a hybrid Clark/Steer Clean algorithm, which takes a dirty map and beam, and produces an output map which consists of the Clean components. This output can be input to SELFCAL to self-calibrate visibilities, or input to RESTOR to produce a "clean" image. Optionally CLEAN can take as one of its inputs a model of the deconvolved image. This model could be from a previous CLEAN run, or from any of the other deconvolution tasks (e.g. MAXEN).  

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 model of the deconvolved image. This could be the output from a previous run of CLEAN, or the output of any of the deconvolution tasks (e.g. MAXEN). It must have flux units of Jy/pixel. The default is no model (i.e. a zero map).
out
The name of the output map. The units of the output will be Jy/pixel. It can be input to RESTOR, CLEAN (as a model, to do more cleaning), or to SELFCAL (for self-calibrating visibility data).
gain
The minor iteration loop gain. Default is 0.1.
cutoff
CLEAN finishes when the absolute maximum residual falls below CUTOFF. Default is 0.
niters
The maximum number of minor iterations. Clean finishes when abs(NITERS) minor iterations have been performed. Clean may finish before this point, however, if NITERS is negative and the absolute maximum residual becomes negative valued, or if the cutoff level (as described above) is reached.
region
This specifies the region to be Cleaned. The default is the largest, centered region that it is safe to deconvolve.
phat
Cornwells prussian hat parameter. When cleaning extended sources, CLEAN may produce a badly corrugated image. This can be suppressed to some extent by cleaning with a dirty beam which has had a spike added at its center (i.e. a beam that looks like a prussian hat). PHAT gives the value of this spike, with 0 to 0.5 being good values. Default is 0 (but use a non-zero value for extended sources).
minpatch
The minimum patch size when performing minor iterations. Default is 51, but make this larger if you are having problems with corrugations. You can make it smaller when cleaning images which consist of a pretty good dirty beam.
speed
This is the same as the speed-up factor in the AIPS APCLN. Negative values makes the rule used to end a major iteration more conservative. This causes less components to be found during a major iteration, and so should improve the quality of the Clean algorithm Usually this will not be needed unless you are having problems with corrugations. A positive value can be useful when cleaning simple point-like sources. Default is 0.
mode
This can be either "hogbom", "clark", "steer" or "any", and determines the Clean algorithm used. If the mode is "any", then CLEAN determines which is the best algorithm to use. The default is "any".
clip
This sets the relative clip level in a Steer clean, values typically being 0.75 to 0.9. The default is image dependent.
server
If this is set to the name of a TV device, then at the end of each major cycle, the restored image is displayed on the TV.


 

Index

NAME
PERSON RESPONSIBLE
CATEGORIES
DESCRIPTION
PARAMETERS

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Time: 18:35:38 GMT, July 05, 2011