Inspect the parameter values of the given task. If given a taskname, sets taskname as the current active (default) task.

  • taskname (obj, string, or None) - task object or task name. None will use current active (default) task.


You can set the values for the parameters for tasks (but currently not for tools) by performing the assignment within the CASA shell and then inspecting them using the inp() command. This command can be invoked in any of three ways: via function call inp('<taskname>') or inp(<taskname>), without parentheses inp '<taskname>' or inp <taskname>, or using the current active (default) task with inp(). For example,

CASA <1>: inp('tclean')
CASA <2>: inp 'tclean'
----------> inp('tclean')
CASA <3>: inp(tclean)
CASA <4>: inp tclean
----------> inp(tclean)
CASA <5>: inp()
----------> inp()

all do the same thing (the final example shows the parameters for the current active task, which is tclean here since the previous line set the current active task to tclean).

When you invoke the task inputs via inp(), you see a list of the parameters, their current values, and a short description of what that parameters does. For example, starting from the default values,

CASA <18>: inp('tclean')
vis = '' # Name of input visibility file(s)
selectdata = True # Enable data selection parameters
field = '' # field(s) to select
spw = '' # spw(s)/channels to select
timerange = '' # Range of time to select from data
uvrange = '' # Select data within uvrange
antenna = '' # Select data based on antenna/baseline
scan = '' # Scan number range
observation = '' # Observation ID range
intent = '' # Scan Intent(s)
datacolumn = 'corrected' # Data column to image(data,corrected)
imagename = '' # Pre-name of output images
imsize = [] # Number of pixels
cell = [] # Cell size
phasecenter = '' # Phase center of the image
stokes = 'I' # Stokes Planes to make
projection = 'SIN' # Coordinate projection
startmodel = '' # Name of starting model image
specmode = 'mfs' # Spectral definition mode (mfs,cube,cubedata, cubesource)
reffreq = '' # Reference frequency
gridder = 'standard' # Gridding options (standard, wproject, widefield, mosaic, awproject)
vptable = '' # Name of Voltage Pattern table
pblimit = 0.2 # PB gain level at which to cut off normalizations
deconvolver = 'hogbom' # Minor cycle algorithm (hogbom,clark,multiscale,mtmfs,mem,clarkstokes)
restoration = True # Do restoration steps (or not)
restoringbeam = [] # Restoring beam shape to use. Default is the PSF main lobe
pbcor = False # Apply PB correction on the output restored image
outlierfile = '' # Name of outlier-field image definitions
weighting = 'natural' # Weighting scheme (natural,uniform,briggs, briggsabs[experimental])
uvtaper = [] # uv-taper on outer baselines in uv-plane
niter = 0 # Maximum number of iterations
usemask = 'user' # Type of mask(s) for deconvolution: user, pb, or auto-multithresh
mask = '' # Mask (a list of image name(s) or region file(s) or region string(s) )
pbmask = 0.0 # primary beam mask
fastnoise = True # True: use the faster (old) noise calculation. False: use the new improved noise calculations
restart = True # True : Re-use existing images. False : Increment imagename
savemodel = 'none' # Options to save model visibilities (none, virtual, modelcolumn)
calcres = True # Calculate initial residual image
calcpsf = True # Calculate PSF
parallel = False # Run major cycles in parallel

The Figure below shows how this will look to you on your terminal. Note that some parameters are in boldface with a gray background. This means that some values for this parameter will cause it to expand, revealing new sub-parameters to be set. Some default values cause the related sub-parameters to be revealed.


CASA uses color and font to indicate different properties of parameters and their values:

Text Font

Text Color





plainblacknonenonestandard parameter
boldblackgreynoneexpandable parameter


plainblacknonenonedefault value
plainbluenonenonenon-default value
plainrednonenoneinvalid value

The Figure below shows what happens when you set some of the tclean parameters to non-default values. Some have opened up sub-parameters, which can now be seen and set. Some have closed sub-parameters because that non-default value has no related sub-parameters. The Figure thereafter shows what happens when you set a parameter to an invalid value. Its value now appears in red. Reasons for invalidation include incorrect type, an invalid menu choice, or a filename that does not exist. For example, since vis expects a filename, it will be invalidated (red) if it is set to a non-string value, or a string that is not the name of a file that can be found. The deconvolver value is invalid because it’s not a supported choice (‘hogbom’, ‘clark’, ‘multiscale’, ‘mtmfs’, ‘mem’, ‘clarkstokes’).


The tclean inputs after setting values away from their defaults (blue text). Note that some of the boldface ones have opened up new dependent sub-parameters (indented and green).


The tclean inputs where one parameter has been set to an invalid value. This is drawn in red to draw attention to the problem. This hapless user probably confused the ‘hogbom’ clean algorithm with Harry Potter.