Release Notes CASA 4.1.0

CASA 4.1.0 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 ALMA, and VLA data, as well as single dish data from ALMA and 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 4.1.0 and later: Major improvements over the previous version of CASA include:

  • Imaging
    • implementation of narrow-band A-projection algorithm
  • Data examination/editing/import/export
    • flagdata and flagcmd can now flag based on calibration tables (e.g. on Tsys)
    • support for multiple input files in flagdata
    • listobs reports a larger number of data parameters, including flagged rows, integration times, spw names
    • new tool msmd with a large number of methods to access meta data information
    • plotms can now display calibration tables (this will eventually replace the current plotcal functionality
    • multi-panel plotting in plotms
    • new task imreframe to change the spectral frame i which the velocity/frequency is reported
    • disabling tool return in tasks to align with general task behavior in CASA and to prevent table locks
  • Calibration
    • expanded use of obsid in all calibration tasks. Calibration solving behavior at ObsId boundaries is now controlled by the combine parameter; by default solutions will not cross ObsId boundaries in CASA v4.1 and later. Interpolation of solutions across ObsId boundaries is controlled by extensions to the interp parameter. Note: Extended ObsId capabilities are available only in CASA 4.1 and higher. Most older caltables will be backward compatible, but without any ObsId capabilities.
    • radial limit to the VLA flux calibrator models (used by setjy)
    • calwt in applycal can now be a vector to enable/disable weight calibration for individual gain tables
    • uvcontsub now allows for specification of corrupted channels to be excluded from the fit in addition to line free channels
    • gencal function to support VLA switched power calibration is now caltype="swpow", requantizer gains can be computed via caltype="rq" and veracity of switched power can be evaluated with caltype='swp/rq'
    • wvrgcal allows a string for the timescale of temporal smoothing
  • Simulation
    • Task simalma uses feather to combine interferometer and total power images.
  • Data and Image Manipulation
    • A graphical interface "casafeather" (run on the Unix command line) to display the feathering weighting functions, scaling and visibility functions of the feather task
    • imregrid has now asvelocity=True as default
  • Data analysis
    • new task impv to create position-velocity diagrams (also available as tool method ia.pv)
    • data analysis tasks now accept specification of channel ranges in the form of velocity ranges
  • Viewer
    • Histogram plotting of data values and Gaussian fitting of these
    • Interactive creation of position-velocity diagrams
    • arbitrary spatial brightness profile slices across images
    • ability to visually set the color transfer function and data range based on intensity value histogram
    • global color option for multiple images
    • the docking behavior can now be set in the ``Preferences'' menu
  • Single Dish
    • new tool method sd.scantable.sub_baseline() allows for independent specification of parameters and function for each baseline per spectrum
    • Baseline fitting results can be stored as a CASA table and applied later
    • new sd tool function sd.scantable.calc_aic() is available to calculate some major values of model selection criteria for a given spectrum and a baseline function.
    • new task sdcal2 for interferometry style calibration (generate caltable and apply caltables)
    • new grid functions GAUSS (Gaussian) and GJINC (Gaussian * Jinc) are available for sdimaging, sdtpimaging, and sdgrid
    • sdimaging: auto calculation of map center when phasecenter is empty
    • sdsave (and sd.splitant): frequency reference frame takes from input MS when data is imported
    • sdgrid: grid positions without any data are flagged
    • sdplot: plottype='pointings' allows overlaying the scan pattern and changing the colors of plot symbols by source type, scan ID, beam ID, polarization ID, or IF number.
    • Nobeyama filler: options to control frequency reference frame, proper handling of dual polarization data, support for data from SAM45
  • Performance
    • sdbaseline speed improvement (2-10 times faster)
    • new experimental task mstransform, which can be used to replace split, cvel, hanningsmooth and partition. The task optimizes the I/O so that all the transformations are applied in memory without the need to read and write multiple times. See for details.
    • The partition task has been modified to use the new MSTransform framework. The interface of partition also changed. The parameters "calmsselection" and "timebin" have been removed. partition now supports channel selections and re-indexes spws after a selection.
  • Other
    • ALMA ATM library upgraded to ALMA-9.4R4
    • added support for "chan" in the CASA CRTF region format

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

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