autoclean – CLEAN an image with automatically-chosen clean regions. – imaging task

Description

Form images from visibilities. Handles continuum and spectral: line cubes. Automatically choose size/shape/position of clean regions.

Parameters

Title
Parameter	Default	Description
vis	`''`
imagename	`''`
field	`''`
spw	`''`
selectdata	`True`
timerange	`''`
uvrange	`''`
antenna	`''`
scan	`''`
mode	`'mfs'`
nchan	`int(1)`
start	`int(0)`
width	`int(1)`
interpolation	`'linear'`
doconcat	`True`
psfmode	`'clark'`
imagermode	`''`
cyclefactor	`float(1.5)`
cyclespeedup	`int(-1)`
imsize	`numpy.array( [ int(256),int(256) ] )`
cell	`{'value': float(1.0), 'unit': 'arcsec'}`
phasecenter	`''`
restfreq	`''`
stokes	`'I'`
weighting	`'natural'`
robust	`float(0.0)`
noise	`'1.0Jy'`
npixels	`int(0)`
interactive	`False`
mask	`numpy.array( [ ] )`
modelimage	`''`
uvtaper	`False`
outertaper	`numpy.array( [ '' ] )`
innertaper	`numpy.array( [ ] )`
niter	`int(500)`
npercycle	`int(100)`
npercycle_speedup	`float(1.5)`
gain	`float(0.1)`
pbcor	`False`
minpb	`float(0.1)`
clean_threshold	`{'value': float(0.0), 'unit': 'mJy'}`
Nrms	`float(6)`
eps_maxres	`float(0.01)`
useabsresid	`False`
allow_maxres_inc	`int(3)`
island_rms	`float(4)`
diag	`False`
peak_rms	`float(6)`
gain_threshold	`float(0.1)`
Npeak	`int(3)`
shape	`int(1)`
boxstretch	`int(1)`
irregsize	`int(100)`

Parameter Explanations

vis

''

Name of input visibility file

imagename

''

Pre-name of output images

field

''

Field Name or id

spw

''

Spectral windows:channels e.g. '0~3:3~100', '' is all

selectdata

True

Other data selection parameters

timerange

''

Range of time to select from data

uvrange

''

Select data within uvrange

antenna

''

Select data based on antenna/baseline

scan

''

Scan number range

mode

'mfs'

Spectral gridding type (mfs, channel, velocity, frequency)

nchan

int(1)

Number of channels (planes) in output image

start

int(0)

First channel in input to use

width

int(1)

Number of input channels to average

interpolation

'linear'

Spectral interpolation(nearest, linear, cubic)

doconcat

True

Concatenate multiple channels into single final image

psfmode

'clark'

Method of PSF calculation to use during minor cycles

imagermode

''

Options: 'csclean' or 'mosaic', ' ', uses psfmode

cyclefactor

float(1.5)

change depth in between of csclean cycle

cyclespeedup

int(-1)

Cycle threshold doubles in this number of iteration

imsize

numpy.array( [ int(256),int(256) ] )

x and y image size in pixels. Single value: same for both

cell

{'value': float(1.0), 'unit': 'arcsec'}

x and y cell size(s). Default unit arcsec.

phasecenter

''

Image center: direction or field index

restfreq

''

Rest frequency to assign to image (see help)

stokes

'I'

Stokes params to image (eg I,IV, QU,IQUV); Current autoclean implementation requires Stokes=”I”.

weighting

'natural'

Weighting of uv (natural, uniform, briggs, …)

robust

float(0.0)

Briggs robustness parameter

noise

'1.0Jy'

noise parameter for briggs abs mode weighting

npixels

int(0)

number of pixels for superuniform or briggs weighting

interactive

False

use interactive clean (with GUI viewer)

mask

numpy.array( [ ] )

Initial cleanbox(es), mask image(s), and/or region(s) used in cleaning

modelimage

''

Name of model image(s) to initialize cleaning

uvtaper

False

Apply additional uv tapering of visibilities

outertaper

numpy.array( [ '' ] )

uv-taper on outer baselines in uv-plane

innertaper

numpy.array( [ ] )

uv-taper in center of uv-plane (not implemented)

niter

int(500)

Max number of total clean cycles per channel

npercycle

int(100)

Clean iterations before adding new clean boxes

npercycle_speedup

float(1.5)

Increase npercycle by this factor if no new regions found.

gain

float(0.1)

Loop gain for cleaning

pbcor

False

Output primary beam-corrected image

minpb

float(0.1)

Minimum PB level to use

clean_threshold

{'value': float(0.0), 'unit': 'mJy'}

Flux level to stop cleaning. Must include units.

Nrms

float(6)

Threshold to stop cleaning: current rms * Nrms

eps_maxres

float(0.01)

Stop cleaning if max abs(residual) changes by less than this factor

useabsresid

False

If True, use absolute value of residual to test for clean convergence.

allow_maxres_inc

int(3)

Stop cleaning if max abs(residual) increases this many times (set to -1 to ignore)

island_rms

float(4)

Threshold for islands when finding clean regions: current rms * island_rms

diag

False

Count diagonal connection as same island?

peak_rms

float(6)

Threshold to add new clean box: peak in island must be at least current rms * peak_rms

gain_threshold

float(0.1)

Threshold to add new clean box: peak in island must be at least current max residual * gain_threshold

Npeak

int(3)

Max number of new clean regions to add in each iteration.

shape

int(1)

Shape of clean regions: 0 for circles, 1 for boxes, 2 for both.

boxstretch

int(1)

Increase clean region size by this many pixels beyond island size.

irregsize

int(100)

For regions this large (in pixels), use irregular clean region.