Release Notes CASA 4.7.2
CASA 4.7.2 is a second patch for 4.7.0 that fixes a bug concerning the restoration of mosaics in tclean. The primary beam correction was inadvertently applied to the model image, which causes problems during cleaning and causes the output restored image to have the primary beam corrected model added to uncorrected residuals, which is incorrect. This behavior is independent of the value of the pbcor parameter (for mosaics the pbcor=True option is not yet implemented). 4.7.1 and 4.7.2 bug fixes are described below as well as features that were introduced in 4.7.0 are listed below.
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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.
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CASA Release Notes:
CASA 4.7.2 bug fixes:
- fixing the bug where a primary beam correction was applied to the model image in tclean
CASA 4.7.1 bug fixes: In addition to delivering update ALMA and VLA pipelines, we fixed the following bugs in CASA:
- Added a correction for the tropospheric delay bug that affects VLA data taken between August 9, 2016, and November 14, 2016. The fix is included in gencal when used with caltype='antpos'.
- A non-standard record of center versus reference frequencies in MTMFS images and FITS files has been resolved.
- importasdm is not failing anymore in the case of mismatched and in particular missing BDFs (this bug was most visible for bdfflags).
- Improved divergence checks in tclean based on peak residuals
- tclean pblimit can now be set as a negative number to omit the application of a Boolean mask in images and residuals.
Valid for CASA Release 4.7.0 and later:
- tclean is a new imaging task, eventually replacing clean. It has a new, more straightforward interface, allows more combinations of algorithms, include options for output files, has a more flexible outlier approach, and includes algorithms for autoboxing. tclean modes that have been commissioned include mfs with nterms=1&2 for both, the standard and mosaic gridders, and spectral line mode cube with the hogbom deconvolver in the LSRK frame. We also tested the common option of restoringbeam and as well as multi-scale clean. Commissioning of additional modes are currently underway, including support for parallel computing. If you find any problems with tclean please send us a note through the CASA helpdesk.
- Data examination/editing/import/export
- plotms for calibration tables is now capable to display tsys, spgain, tec, and SNR axes
- polarization selection for calibration tables in plotms
- plotms has a new option to average across fields
- plotms displays the reference frame for frequency axes
- plotms has now the ability to set font size for labels
- height, width and dpi has been added to the plotms task export feature
- plotms does now allow one to iterate over correlation
- pre-averaging in flagdata
- setjy is now performing linear interpolation of model values
- new asteroid flux models are now available in setjy
- new standard "Stevens-Reynolds 2016" for an updated flux density polynomial of 1934-638
- new cb.createcaltable tool method to create empty calibration table
- Data and Image Manipulation
- New task: plotprofilemap to show a "profile map" of CASA image data, as spectra binned up over user-defined boxsize, in RA/Dec.
- msmd can retrieve spw ids from spw names
- improved image processing histories are now recorded in CASA images
- imsubimage has options to drop degenerate axes
- imhead now also returns a python dictionary
- immath allows specification of an image that is used to define the metadata of the output image
- imsmooth scales images with units Jy/beam and Jy/beam.km/s via the inverse of their beams but leaves images with other units unscaled by default
- Data analysis
- new task specflux reports spectral line characteristics when averaged over a region
- ia.findsources does now accept Jy/beam.km/s images
- masks will be stretched individually when they are used in immath LEL expressions
- improved ASCII file output format for imfit
- The precision of the spectral coordinate labeling can now be selected
- contour thickness can be set in imview
- Single Dish
- New task: sdgaincal: Uses mode='doublecircle' and interpolates time-dependet gain variation for Fast-Mapped Double circle observations.
- New task: importnro: Convert Nobeyama NOSTAR format to ASDM format.
- New task/parameter in sdimaging: clipminmax; rejects the maximum and minimum values of the data ensemble used to compute pixel values during gridding.
- Extended task: sdimaging accepts and rounds float values input to imsize and cellsize
- Extended task: sdimaging selects target intents by default
- New fitmode in tsdfit: fitmode='auto'; auto-detect line emission and return gaussian fit characteristics
- New function/parameter in sdbaseline: blfunc='sinusoid', enables removal of selected (or dominant) fourier components from spectral data.
- New calmode in tsdcal: calmode='otf': Generation of sky calibration table assuming integrations at a map edge as off source measurements. Map edge detection is operated on the offset coordinate with respect to the source for known moving sources, e.g., Sun, Moon, etc."
- Parallelization of tclean is still underway
- new Jansky VLA beams are now available
- Experimental tasks
- tclean testing of some modes is still underway, this includes parallelization of the imaging processes
- new task: visstat2 (MS-format replacement for sdstat and visstat)
- mstransform has an experimental addition to perform continuum subtraction