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casa
$Rev:20696$
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casa
$Rev:20696$
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Functions | |
| def | autoclean |
| def autoclean.autoclean | ( | vis = '', |
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imagename = '', |
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field = '', |
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spw = '', |
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selectdata = True, |
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timerange = '', |
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uvrange = '', |
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antenna = '', |
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scan = '', |
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mode = 'mfs', |
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nchan = 1, |
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start = 0, |
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width = 1, |
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interpolation = 'linear', |
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doconcat = True, |
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psfmode = 'clark', |
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imagermode = '', |
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cyclefactor = 1.5, |
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cyclespeedup = -1, |
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imsize = [256, |
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cell = ['1.0arcsec'], |
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phasecenter = '', |
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restfreq = '', |
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stokes = 'I', |
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weighting = 'natural', |
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robust = 0.0, |
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noise = '1.0Jy', |
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npixels = 0, |
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interactive = False, |
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mask = [], |
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modelimage = '', |
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uvtaper = False, |
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outertaper = [''], |
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innertaper = ['1.0'], |
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niter = 500, |
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npercycle = 100, |
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npercycle_speedup = 1.5, |
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gain = 0.1, |
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pbcor = False, |
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minpb = 0.1, |
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clean_threshold = '0.0mJy', |
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Nrms = 6, |
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eps_maxres = 0.01, |
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useabsresid = False, |
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allow_maxres_inc = 3, |
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island_rms = 4, |
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diag = False, |
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peak_rms = 6, |
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gain_threshold = 0.1, |
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Npeak = 3, |
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shape = 1, |
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boxstretch = 1, |
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irregsize = 100 |
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| ) |
CLEAN an image with automatically-chosen clean regions.
This is a wrapper for clean which includes automatic clean boxing.
Current capabilities include:
1) Multi-frequency-continuum images or spectral channel imaging
2) Stokes I imaging only
3) Use starting mask
vis -- Name of input visibility file
default: none; example: vis='ngc5921.ms'
imagename -- Pre-name of output images:
default: none; example: imagename='m2'
output images are:
m2.image; cleaned and restored image
With or without primary beam correction
m2.psf; point-spread function (dirty beam)
m2.flux; relative sky sensitivity over field
m2.mask; total clean regions
m2.model; image of clean components
m2.residual; image of residuals
field -- Select fields in mosaic. Use field id(s) or field name(s).
['go listobs' to obtain the list id's or names]
default: ''= all fields
If field string is a non-negative integer, it is assumed to
be a field index otherwise, it is assumed to be a
field name
field='0~2'; field ids 0,1,2
field='0,4,5~7'; field ids 0,4,5,6,7
field='3C286,3C295'; field named 3C286 and 3C295
field = '3,4C*'; field id 3, all names starting with 4C
spw -- Select spectral window/channels
NOTE: This selects the data passed as the INPUT to mode
default: ''=all spectral windows and channels
spw='0~2,4'; spectral windows 0,1,2,4 (all channels)
spw='0:5~61'; spw 0, channels 5 to 61
spw='<2'; spectral windows less than 2 (i.e. 0,1)
spw='0,10,3:3~45'; spw 0,10 all channels, spw 3,
channels 3 to 45.
spw='0~2:2~6'; spw 0,1,2 with channels 2 through 6 in each.
spw='0:0~10;15~60'; spectral window 0 with channels
0-10,15-60
spw='0:0~10,1:20~30,2:1;2;3'; spw 0, channels 0-10,
spw 1, channels 20-30, and spw 2, channels, 1,2 and 3
selectdata -- Other data selection parameters
default: True
>>> selectdata=True expandable parameters
See help par.selectdata for more on these
timerange -- Select data based on time range:
default: '' (all); examples,
timerange = 'YYYY/MM/DD/hh:mm:ss~YYYY/MM/DD/hh:mm:ss'
Note: if YYYY/MM/DD is missing date defaults to first
day in data set
timerange='09:14:0~09:54:0' picks 40 min on first day
timerange='25:00:00~27:30:00' picks 1 hr to 3 hr
30min on NEXT day
timerange='09:44:00' pick data within one integration
of time
timerange='>10:24:00' data after this time
uvrange -- Select data within uvrange (default units meters)
default: '' (all); example:
uvrange='0~1000klambda'; uvrange from 0-1000 kilo-lambda
uvrange='>4klambda';uvranges greater than 4 kilo lambda
antenna -- Select data based on antenna/baseline
default: '' (all)
If antenna string is a non-negative integer, it is
assumed to be an antenna index, otherwise, it is
considered an antenna name.
antenna='5&6'; baseline between antenna index 5 and
index 6.
antenna='VA05&VA06'; baseline between VLA antenna 5
and 6.
antenna='5&6;7&8'; baselines 5-6 and 7-8
antenna='5'; all baselines with antenna index 5
antenna='05'; all baselines with antenna number 05
(VLA old name)
antenna='5,6,9'; all baselines with antennas 5,6,9
index numbers
scan -- Scan number range.
default: '' (all)
example: scan='1~5'
Check 'go listobs' to insure the scan numbers are in
order.
mode -- Frequency Specification:
NOTE: Channels deselected with spw parameter will contain all
zeros.
See examples below.
default: 'mfs'
mode = 'mfs' means produce one image from all
specified data.
mode = 'channel'; Use with nchan, start, width to specify
output image cube. See examples below
mode = 'velocity', means channels are specified in
velocity.
mode = 'frequency', means channels are specified in
frequency.
>>> mode expandable parameters (for modes other than 'mfs')
Start, width are given in units of channels, frequency
or velocity as indicated by mode (note: only nearest neighbour
interpolation is available at this time).
nchan -- Number of channels (planes) in output image
default: 1; example: nchan=3
start -- Start input channel (relative-0)
default=0; example: start=5
width -- Output channel width in units of the input
channel width (>1 indicates channel averaging)
default=1; example: width=4
interpolation -- Interpolation type of spectral data when gridded on
the uv-plane
default = 'linear'
doconcat -- Tells autoclean to concatenate multiple channel images into
single image at the end of its run. (Autoclean makes an image
for each channel, and cleans/boxes them one at a time.)
default = 'True'
examples:
spw = '0,1'; mode = 'mfs'
will produce one image made from all channels in spw
0 and 1
spw='0:5~28^2'; mode = 'mfs'
will produce one image made with channels
(5,7,9,...,25,27)
spw = '0'; mode = 'channel': nchan=3; start=5; width=4
will produce an image with 3 output planes
plane 1 contains data from channels (5+6+7+8)
plane 2 contains data from channels (9+10+11+12)
plane 3 contains data from channels (13+14+15+16)
spw = '0:0~63^3'; mode='channel'; nchan=21; start = 0;
width = 1
will produce an image with 20 output planes
Plane 1 contains data from channel 0
Plane 2 contains date from channel 2
Plane 21 contains data from channel 61
spw = '0:0~40^2'; mode = 'channel'; nchan = 3; start =
5; width = 4
will produce an image with three output planes
plane 1 contains channels (5,7)
plane 2 contains channels (13,15)
plane 3 contains channels (21,23)
psfmode -- method of PSF calculation to use during minor cycles:
default: 'clark': Options: 'clark','clarkstokes', 'hogbom'
'clark' use smaller beam (faster, usually good enough);
for stokes images clean components peaks are searched in the I^2+Q^2+U^2+V^2 domain
'clarkstokes' locate clean components independently in each stokes image
'hogbom' full-width of image (slower, better for poor
uv-coverage)
Note: psfmode will be used to clean is imagermode = ''
imagermode -- Advanced imaging e.g mosaic or Cotton-Schwab clean
default: imagermode='': Options: '', 'csclean'
default '' => psfmode cleaning algorithm used
>>> imagermode='csclean' expandable parameter(s):
Image using the Cotton-Schwab algorithm in between major cycles
cyclefactor -- Change the threshold at which
the deconvolution cycle will stop, degrid
and subtract from the visibilities. For
poor PSFs, reconcile often (cyclefactor=4 or
5); For good PSFs, use cyclefactor 1.5 to
2.0. Note: threshold = cyclefactor * max
sidelobe * max residual.
default: 1.5; example: cyclefactor=4
cyclespeedup -- Cycle threshold doubles in this
number of iterations default: -1;
example: cyclespeedup=3
try cyclespeedup = 50 to speed up cleaning
imsize -- Image pixel size (x,y). DOES NOT HAVE TO BE A POWER OF 2
default = [256,256]; example: imsize=[350,350]
imsize = 500 is equivalent to [500,500]
Avoid odd-numbered imsize.
cell -- Cell size (x,y)
default= '1.0arcsec';
example: cell=['0.5arcsec,'0.5arcsec'] or
cell=['1arcmin', '1arcmin']
cell = '1arcsec' is equivalent to ['1arcsec','1arcsec']
NOTE:cell = 2.0 => ['2arcsec', '2arcsec']
phasecenter -- direction measure or fieldid for the mosaic center
default: '' => first field selected ; example: phasecenter=6
or phasecenter='J2000 19h30m00 -40d00m00'
restfreq -- Specify rest frequency to use for output image
default='' Occasionally it is necessary to set this (for
example some VLA spectral line data). For example for
NH_3 (1,1) put restfreq='23.694496GHz'
stokes -- Stokes parameters to image
default='I'; example: stokes='IQUV';
Options: 'I','IV''QU','IQUV','RR','LL','XX','YY','RRLL','XXYY'
weighting -- Weighting to apply to visibilities:
default='natural'; example: weighting='uniform';
Options: 'natural','uniform','briggs',
'superuniform','briggsabs','radial'
>>> Weighting expandable parameters
For weighting='briggs' and 'briggsabs'
robust -- Brigg's robustness parameter
default=0.0; example: robust=0.5;
Options: -2.0 to 2.0; -2 (uniform)/+2 (natural)
For weighting='briggsabs'
noise -- noise parameter to use for Briggs "abs"
weighting
example noise='1.0mJy'
npixels -- uv-cell area used for weight calculation
example npixels=1
Default = 0
superuniform: 0 Means 3x3 cells for weighting
the cell weight is proportional to the weight of
the 3x3 cells centered on it.
superuniform = F means 1x1 cell for averaging weights.
briggs/briggsabs: 0 is similar to 1x1 cell weight.
1 may? be similar to 3X3 cells.
Only npixels 0 or 1 recommended
mask -- Initial specification of cleanbox(es), mask image(s), and/or
region(s) to be used for CLEANing. For channel data (image cubes),
any initial mask will be applied to every channel. mask default:
[] (no masking); Possible specification types: (a) Explicit
cleanbox pixel ranges example: mask=[110,110,150,145] clean
region with blc=110,100; trc=150,145 (pixel values) (b)
Filename with cleanbox pixel values with ascii format:
example: mask='mycleanbox.txt' <fieldid blc-x blc-y
trc-x trc-y> on each line
1 45 66 123 124
2 23 100 300 340
(c) Filename for image mask example: mask='myimage.mask'
(d) Filename for region specification (e.g. from viewer)
example: mask='myregion.rgn' (e) Combinations of any of the
above example: mask=[[110,110,150,145],'mycleanbox.txt',
'myimage.mask','myregion.rgn']
If include outlier fields, then mask need to be spefied in
nested lists: e.g. mask=[[[110,110,150,145],'myimage.mask'],[],[20,20,40,40]]
(A clean box with [110,110,150,145] and a image mask for main field,
no mask for 1st outlier field, 1 clean box for second outlier field.)
modelimage -- Name of model image(s) to initialize cleaning. If
multiple images, then these will be added together to
form initial starting model NOTE: these are in addition
to any initial model in the <imagename>.model image file
default: '' (none); example: modelimage='orion.model'
modelimage=['orion.model','sdorion.image'] Note: if the
units in the image are Jy/beam as in a single-dish
image, then it will be converted to Jy/pixel as in a
model image, using the restoring beam in the image
header
>>> uvtaper=True expandable parameters
outertaper -- uv-taper on outer baselines in uv-plane
[bmaj, bmin, bpa] taper Gaussian scale in uv or
angular units. NOTE: uv taper in (klambda) is roughly on-sky
FWHM(arcsec/200)
default: outertaper=[]; no outer taper applied
example: outertaper=['5klambda'] circular taper
FWHM=5 kilo-lambda
outertaper=['5klambda','3klambda','45.0deg']
outertaper=['10arcsec'] on-sky FWHM 10"
outertaper=['300.0'] default units are meters
in aperture plane
innertaper -- uv-taper in center of uv-plane
[bmaj,bmin,bpa] Gaussian scale at which taper falls to
zero at uv=0
default: innertaper=[]; no inner taper applied
NOT YET IMPLEMENTED
niter -- Maximum number iterations over all clean iterations.
default: 500; example: niter=5000
npercycle -- Number of clean minor cycles before making new clean region
selection.
default: 100; example: npercycle = 100
npercycle_speedup: If no new clean regions found during an iteration of
clean region selections, increase npercycle by this factor.
(Npercycle returns to initial value if new clean regions are later
found.)
default: 1.5; example: npercycle_speedup = 2
gain -- Loop gain for CLEANing
default: 0.1; example: gain=0.5
pbcor -- Output primary beam-corrected image
default: pbcor=False; output un-corrected image
example: pbcor=True; output pb-corrected image (masked outside
minpb) Note: if you set pbcor=False, you can later
recover the pbcor image by dividing by the .flux image
(e.g. using immath)
minpb -- Minimum PB level to use default=0.1;
The flux image is used to determine this
except for the case of mosaic with ft='mosaic'
where the flux.pbcoverage image is used.
example:
minpb=0.01 Note: this minpb is always in effect
(regardless of pbcor=True/False)
clean_threshold -- Flux level at which to stop CLEANing
default: '0.0mJy';
example: threshold='2.3mJy' (always include units)
threshold = '0.0023Jy'
threshold = '0.0023Jy/beam' (okay also)
Nrms -- Stop cleaning when maximum residual is below this value times
the current rms (outside the current clean regions).
default: 6
example: Nrms=4
eps_maxres -- Convergence parameter to stop cleaning: stop if maximum
residual has changed by less than a factor of eps_maxres.
default: 0.01 (one per cent change)
example: eps_maxres = 0.05
allow_maxres_inc -- Parameter to stop cleaning: stop if maximum residual
has increased between clean iterations this number of times.
default: 3
example: allow_maxres_inc = 2
island_rms: threshold (this value times current rms) at which to box the
residual image when searching for new clean regions
default: 4
example: island_rms = 3
diag: T/F switch to declare if pixels connected on the diagonal belong
to the same island, when selecting pixels for clean boxing
default: False
example: diag = True
peak_rms: threshold (this value times current rms) for peak pixel flux
to qualify an island for clean boxing
default: 6
example: peak_rms = 5
gain_threshold: threshold (this value times current maximum residual) of
peak pixel in island to qualify island for clean boxing.
default: 0.1
example: gain_threshold = 0.5
Npeak: maximum number of new clean regions to add each iteration
default: 3
example: Npeak = 5
shape: parameter to determine shape of clean regions.
0: all circles
1: all boxes
2: choose according to island shape (circles if island has similar
dimension in x and y direction, box otherwise)
default: 1
example: shape=2
boxstretch: number of pixels to increase outward size of clean region,
can range from -1 to 5.
default: 1
example: boxstretch = 3
irregsize: for islands this large (dimension in pixels) or larger, fill
in mask with island's actual shape rather than using a box or
circle. Set to 0 to ignore this parameter.
default: 100
example: irregsize = 50Definition at line 13 of file autoclean.py.
References task_autoclean.autoclean(), publish_summary.quantity, and vla_uvfits_line_sf.verify.
1.8.0