casatasks

Tasks in CASA are python interfaces to the more basic toolkit. Tasks are executed to perform a single job, such as loading, plotting, flagging, calibrating, and imaging the data.

The parameters used and their defaults can be obtained by typing help(<taskname>) at the Python prompt, where <taskname> is the name of a given task. This command lists all parameters, a brief description of the parameter, the parameter default, and any options if there are limited allowed values for the parameter.

Experimental tasks and algorithms

Some tasks and algorithms in CASA are labelled as Experimental or Unverified. These tasks have not been fully commissioned and/or verified. Such tasks are provided to enhance user capabilities, or because they are required for specific pipeline use.

The label Experimental or Unverified means that the task/algorithm falls under the following disclaimers:

• Only a subset of modes have been incorporated into CASA unit/regression tests. These are documented in CASA Docs. Other options/modes may be run, and might work just fine, but they are not part of what has been tested carefully.

• Some parameters have been tested for specific use cases (as part of the algorithm development, publication, and CASA test programs), but we have not yet established best practices for all different situations. This information will build over time and will be incorporated into our documentation as appropriate.

• Experimental tasks and algorithms may have Known Issues, representing CASA's current understanding of the state of the code. These Known Issues are clearly defined as part of CASA Docs.

• Parameter names and task structure can change, based on feedback and improved understanding of usability.

It is expected that ALMA and VLA pipelines will begin using experimental tasks only after they have stabilized for stand-alone use.

The complete listing of tasks available in CASA is as follows:

Input / Output

exportasdm	Convert a CASA visibility file (MS) into an ALMA or EVLA Science Data Model
exportfits	Convert a CASA image to a FITS file
exportuvfits	Convert a CASA visibility data set to a UVFITS file:
getephemtable	Query the JPL-Horizons database for ephemeris data and create a CASA table
importasdm	Convert an ALMA Science Data Model observation into a CASA visibility file (MS)
importatca	Import ATCA RPFITS file(s) to a measurement set
importfits	Convert an image FITS file into a CASA image
importfitsidi	Convert a FITS-IDI file to a CASA visibility data set
importgmrt	Convert a UVFITS file to a CASA visibility data set
importmiriad	Convert a Miriad visibility file into a CASA MeasurementSet
importuvfits	Convert a UVFITS file to a CASA visibility data set
importvla	Import VLA archive file(s) to a measurement set
splattotable	Convert a downloaded Splatalogue spectral line list to a casa table.

Information

asdmsummary	Summarized description of an ASDM dataset.
calstat	Calculates statistical information on a calibration table
imhead	List, get and put image header parameters
imhistory	Retrieve and modify image history
imstat	Calculates statistical information from an image or image region
listcal	List antenna gain solutions
listfits	List the HDU and typical data rows of a fits file:
listhistory	List the processing history of a dataset:
listobs	Get the summary of a MeasurementSet and list it in the logger or in a file
listpartition	Get the summary of a multi-MS data set and print in the logger or in a file
listsdm	Lists observation information present in an SDM directory.
listvis	List measurement set visibilities.
slsearch	Search a spectral line table.
vishead	List, summary, get, and put metadata in a measurement set
visstat	Calculates statistical information from a MeasurementSet

Flagging

flagcmd	Flagging task based on batches of flag-commands
flagdata	All-purpose flagging task based on data-selections and flagging modes/algorithms.
flagmanager	Enable list, save, restore, delete and rename flag version files.

Calibration

accor	Normalize visibilities based on auto-correlations
applycal	Apply calibrations solutions(s) to data
bandpass	Calculates a bandpass calibration solution
blcal	Calculate a baseline-based calibration solution (gain or bandpass)
clearcal	Re-initializes the calibration for a visibility data set
defintent	Manually set scan intents
fluxscale	Bootstrap the flux density scale from standard calibrators
fringefit	Fringe fit delay and rates
gaincal	Determine temporal gains from calibrator observations
gencal	Specify Calibration Values of Various Types
getantposalma	Retrieve antenna positions by querying ALMA web service.
getcalmodvla	Retrieve calibrator brightness distributions from a VLA web service.
initweights	Initializes weight information in the MS
polcal	Determine instrumental polarization calibrations
polfromgain	Derive linear polarization from gain ratio
rerefant	Re-apply refant to a caltable
smoothcal	Smooth calibration solution(s) derived from one or more sources
wvrgcal	Generate a gain table based on Water Vapour Radiometer data

Imaging

apparentsens	Imaging sensitivity estimation
deconvolve	Image-domain deconvolution
delmod	Deletes model representations in the MS
feather	Combine two images using their Fourier transforms
ft	Insert a source model as a visibility set
impbcor	Construct a primary beam corrected image from an image and a primary beam pattern.
makemask	Makes and manipulates image masks
predictcomp	Make a component list for a known calibrator
sdintimaging	Form images from interferometric visibilities and single dish image to reconstruct a sky model by joint deconvolution.
setjy	Fills the model column with the visibilities of a calibrator
tclean	Radio Interferometric Image Reconstruction
widebandpbcor	Wideband PB-correction on the output of the MS-MFS algorithm

Single Dish

importasap	Convert ASAP Scantable data into a CASA visibility file (MS)
importnro	Convert NOSTAR data into a CASA visibility file (MS)
nrobeamaverage	Average SD data over beams and do time averaging
sdatmcor	Offline correction of residual atmospheric features
sdbaseline	Fit/subtract a spectral baseline
sdcal	MS SD calibration task
sdfit	Fit a spectral line
sdfixscan	Task for single-dish image processing
sdgaincal	MS SD gain calibration task
sdimaging	SD task: imaging for total power and spectral data
sdpolaverage	Average SD spectra over polarisation
sdsidebandsplit	[EXPERIMENTAL] invoke sideband separation using FFT
sdsmooth	Smooth spectral data
sdtimeaverage	Average SD data, perform time averaging
tsdimaging	SD task: imaging for total power and spectral data

Manipulation

clearstat	Clear all autolock locks
concat	Concatenate several visibility data sets.
conjugatevis	Change the sign of the phases in all visibility columns.
cvel	regrid an MS to a new spectral window / channel structure or frame
cvel2	Regrid an MS or MMS to a new spectral window, channel structure or frame
fixplanets	Changes FIELD and SOURCE table entries based on user-provided direction or POINTING table, optionally fixes the UVW coordinates
fixvis	Recalculates (u, v, w) and/or changes Phase Center
hanningsmooth	Hanning smooth frequency channel data to remove Gibbs ringing
mstransform	Split the MS, combine/separate/regrid spws and do channel and time averaging
msuvbin	grid the visibility data onto a defined uniform grid (in the form of an ms); multiple MS's can be done onto the same grid
partition	Task to produce Multi-MSs using parallelism
phaseshift	Rotate a Measurement Set to a new phase-center
rmtables	Remove tables cleanly, use this instead of rm -rf
split	Create a visibility subset from an existing visibility set
statwt	Compute and set weights based on variance of data.
uvcontsub	continuum subtraction in the uv domain
uvcontsub_old	Continuum fitting and subtraction in the uv plane
uvmodelfit	Fit a single component source model to the uv data
uvsub	Subtract/add model from/to the corrected visibility data.
virtualconcat	Concatenate several visibility data sets into a multi-MS

Analysis

imbaseline	Image-based baseline subtraction for single-dish data
imcollapse	Collapse image along one axis, aggregating pixel values along that axis.
imcontsub	Estimates and subtracts continuum emission from an image cube
imdev	Create an image that can represent the statistical deviations of the input image.
imfit	Fit one or more elliptical Gaussian components on an image region(s)
immath	Perform math operations on images
immoments	Compute moments from an image
impv	Construct a position-velocity image by choosing two points in the direction plane.
imrebin	Rebin an image by the specified integer factors
imreframe	Change the frame in which the image reports its spectral values
imregrid	regrid an image onto a template image
imsmooth	Smooth an image or portion of an image
imsubimage	Create a (sub)image from a region of the image
imtrans	Reorder image axes
imval	Get the data value(s) and/or mask value in an image.
rmfit	Calculate rotation measure
specfit	Fit 1-dimensional gaussians and/or polynomial models to an image or image region
specflux	Report spectral profile and calculate spectral flux over a user specified region
specsmooth	Smooth an image region in one dimension
spxfit	Fit a 1-dimensional model(s) to an image(s) or region for determination of spectral index.

Visualization

plotants	Plot the antenna distribution in the local reference frame
plotbandpass	Makes detailed plots of Tsys and bandpass solutions.
plotprofilemap	Makes profile map
plotweather	Plot elements of the weather table; estimate opacity

Simulation

simalma	Simulation task for ALMA
simanalyze	image and analyze measurement sets created with simobserve
simobserve	visibility simulation task