Release Notes CASA 4.0.1

CASA 4.0.0 is now available and the main feature improvements are listed below. In addition to the new features, many bugs were addressed and fixed.

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Note that in its current incarnation CASA is designed to support EVLA, ALMA, and VLA data, as well as single dish data from ALMA as well as Nobeyama. Data from other telescopes, be it single dish or interferometers can be imported from uvfits, FITS-IDI , or sdfits formats into measurements sets (ms) or scantables in CASA. Given the variety of non-standard fits formats, we cannot guarantee that CASA will fully support data from all telescopes. However, efforts are made to support data formats from other facilities.

Obtaining the CASA Release

This version of CASA is available from our Download page. There, we also list the supported operating systems.

CASA Release Notes:

Valid for CASA Release 4.0.0 and later: Major improvements over the previous version of CASA include:

  • Flagging
    • tflagdata has been renamed flagdata. The old flagdata no longer exists. The new flagdata task contains a new feature when mode='list' is used. The sub-parameter inpfile can take in either a file or a list of Python strings containing the flag commands.
    • flagcmd mode='file' is renamed as mode='list', and can take in either a file name containing flag commands, or a Python list of strings such as: [ '...', '...' ]. Since this duplicates the mode='cmd' in flagcmd, the 'cmd' option will be dropped. This unifies the parameter sets for flagdata and flagcmd.
    • flagdata2, flagautocorr and oldflagcmd have been removed.
  • Imaging
    • Up to four threads can now be used in the visibility gridding step (for ftmachine 'ft' and 'wproject')
    • spectral line imaging in parallel cleaning (pclean) as well as continuum mode ( mode='mfs';nterms=1) for single fields and mosaics is available
    • improved performance and usability of parallel cleaning (pclean), including CASA region support
    • for large fractional bandwidths, clean will now use per-channel restoring beams
    • primary beam correction for Taylor-term nterms>1 continuum images is now available in the new task widebandpbcor
    • usescratch=F is now the default in clean (triggering the use of an attached model image)
  • Data examination/editing
    • plotms: Selections of data points can now be dumped into ASCII files
    • scriptability and autosizing of point sizes
  • Calibration
    • Support for calibration of linear polarization feeds
    • using nearest in the gainfield parameter will select the field id with the shortest distance on the sky
    • gencal can now create calibration tables from gaincurves and antenna efficiencies - this method replaces the gaincurve and opacity parameters in calibration tasks
    • more flexible flagging modes in applycal with the new applymode parameter
    • fluxscale now produces a calibration table with only the relative scaling factors per spw. The new fluxscale table is to be used in combination with the amplitude (vs. time) calibration table rather than as a replacement.
    • fluxscale outputs a spectral index and curvature that can be used as input for setjy
    • fluxscale now uses the median instead of the average for the flux scaling
    • setjy now contains updated models for solar system objects ('Butler-JPL-Horizons 2012')
    • first implementation of 'Perley-Butler 2013' flux standard in setjy
    • usescratch=F is now the default in setjy (i.e. use of the virtual model column is now the default)
    • wvrgcal is updated to version 1.2
  • Simulation
    • new experimental task simalma to simulate ALMA observation (main array + ACA + Total Power single dish)
    • task simdata is now removed as all functionality is in other tasks, namely simobserve and simanalyze
  • Data and Image Manipulation
    • new task imsubimage to more easily create subsets of data cubes
    • new task makemask for handling of masks in images
    • new parameter respectname in concat which, if True, makes concat regard two fields with the same direction but different name as different fields.
    • new task conjugatevis to change the sign of the phases of visibilities
  • Data analysis
    • support for different beamsizes per plane (as an output from clean) in all image analysis tasks
  • Viewer
    • on-the-fly spectral velocity regridding when multiple data cubes are selected
    • "blinking" images and moving through the image spectral planes are now separated into two separate tapedecks.
    • FITS & CASA preload image summaries in Data Manager panel
    • Rework of Data Manager with tabs for saving images and regions
    • additional marker shapes for point-type regions
    • Substantial improvements have been made to the spectral viewer, including:
      • The plane displayed in the image panel is now marked in and can be selected or scrolled from the spectral viewer
      • The units on the y-axis can now be changed and when a single cube is loaded, multiple x-axis labels can be shown at the same time (e.g. velocity and frequency)
      • Plotting colors, the legend location, and the plot style (histogram/line) can now be customized and persist
      • Initial implementation of spectral line catalog overlays and interactive spectral line identification.
      • Initial implementation of on-the-fly moment creation via the "Collapse" tool.
      • The position of the spectral profile can now be specified by typing in a coordinate or pixel location.
  • Single Dish
    • OTF map calibration can now use the edge of the map as a reference as an alternative to separate reference scan observations
    • Added new calmodes, 'otf' and 'otfraster', in sdcal task
    • improved exiting options from sdbaseline, sdcal, sdsmooth
    • sdplot: new plottype='grid' to plot spectra based on their sky position.
    • sdflag: ability to view flagged data on interactive flag plotter.
    • sdplot accepts CASA-type selection syntax in scanlist, iflist, pollist and beamlist parameters.
    • Chebychev polynomial fitting in sdbaseline
    • Rest Frequency Parameter available in sdbaseline, sdfit, sdflag, sdimaging, sdplot, sdreduce, sdsave and sdstat.
    • Sdflag: channel flagging by frequency or velocity available now.
  • Performance
    • experimental parallelization of most visibility-related tasks (but excluding those that produce new output MSs). Inprovements include
      • multi-MS (MMS) are now self-contained and can be moved, copied and renamed like normal MSs
      • reliability improvements on partition
      • new task listpartition displays partition information of an MMS
      • new parameter keepmms in split enables MMS output when the input is an MMS (makes repartitioning superfluous, especially useful in the case of splitting out the corrected data or for spectral averaging)
  • Other
    • binding of C++ code to python is now performed via swig

For more information, see the Known Issues page, and for general reference see the Using CASA help and documentation page.

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