Examples
This task does not do a uvdata subtraction (aka Cotton-Schwab major cycle) of model visibility as in clean. - For ALMA Commissioning
Keyword arguments:
vis -- Name of input visibility file
default: none; example: vis='ngc5921.ms'
imagename -- Name of output CASA image. (only the prefix)
default: none; example: imagename='m2'
output images are:
m2.image; cleaned and restored image
With or without primary beam correction
m2dirty.image; dirty image
m2psf.image; point-spread function (dirty beam)
m2.model; image of clean components
m2.mask; image containing clean regions, when interative=True
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
advise -- This determines whether advice for imsize and cell is
requested. If set to True. It won't run clean but return
values for imszise and cell estimated for the longest
baseline in the data
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'
mode -- this determines what kind of image to make
continuum or cube. In continuum all the selected data
channels are combined in a 1 channel image using
multifrequency synthesis.
options are 'cube' and 'continuum'
default: 'continuum'
>>> mode='cube' expandable parameters
nchan -- sets the number of channel in the output
image. e.g nchan=10
width -- image channel width in terms of the number of
channel of the first spw of the data selected
e.g width=2
niter -- Maximum number of iterations,
if niter=0, then no CLEANing is done ("invert" only)
default: 500; example: niter=5000
weighting -- Weighting to apply to visibilities:
default='natural'; example: weighting='uniform';
Options: 'natural','uniform','briggs',
'superuniform','briggsabs','radial'
restoringbeam -- Output Gaussian restoring beam for CLEAN image
[bmaj, bmin, bpa] elliptical Gaussian restoring beam.
Default units are in arc-seconds for bmaj and bmin, and in degrees
for bpa. Default: restoringbeam=[]; Use PSF calculated
from dirty beam.
example: restoringbeam=['10arcsec'] or restorinbeam='10arcsec', circular Gaussian.
FWHM 10 arcseconds example:
restoringbeam=['10.0','5.0','45.0deg'] 10"x5"
at 45 degrees
interactive -- Create a mask interactively or not.
default=False; example: interactive=True
The viewer will open with the image displayed. Select the
region for the mask and double click in the middle of it.