WSClean version 2.6

Released 2018-06-11

Summary: A “lots of little improvements” update, with no major changes at this time. Interesting new features are some very specific cleaning modes, like linked polarizations and parallel cleaning.

Major & visible changes:

  • Support for “parallell cleaning” (option ‘-parallel-clean’), which splits up images using a path search algorithm, and allows faster and clean and larger images.

  • Polarization-linked cleaning (’-link-polarizations’), which allows cleaning a set polarizations using information from another set of polarizations (e.g. clean QUV only using I information).

  • Support for calculating AARTFAAC primary beam.

  • Tapering is now taken into account in the initial value of the PSF, thereby improving fit stability on tapered runs (SF #134, reported by P. Serra)

  • Circular and non-circular Gaussian fitter improvements (related to SF #134).

  • Added option ‘-beam-fitting-size’ to allow changing the fitting box size (useful for MSSS).

  • Added option ‘-divide-channels-by-gaps’, which changes how bandwidth is splitted in multiple-output-channels mode.

  • Adding option ‘-pb-undersampling’ to turn off or change undersampling.

  • Added parameter ‘-lofar-centroids’, which takes centroid information into account. This was an experiment, and seemed not to be very useful (it is very slow and does not improve accuracy).

  • WSClean can now grid only the even or odd timesteps (parameters ‘-even-timesteps’ and ‘-odd-timesteps’). Useful for certain experiments, e.g. estimating noise value (SF #133).

  • Option ‘-no-normalize-for-weighting’ was removed, as keywords can be used to scale images appropriately.

  • Accept 3d fits masks that have velocity instead of frequency as 3rd axis (reported by M. Ramatsoku).

  • Provide an error message when automasking threshold <= auto threshold.

  • Removing -force-dynamic-join option, as it is no longer necessary to specify it.

  • IDG command line parameters have been added to the command line help.

Bugfixes / technical changes:

  • CMake findcasacore script updated to fix unresolved symbols with certain Casacore versions.

  • Model column was not updated when using ‘-continue’ (reported by R. van Weeren and G. Di Gennaro).

  • One-off error in calculating of nr scans, and reporting proper error when requesting more intervals than available (SF #131, reported by S. Bourke)

  • When writing model data back to MS, progress bar did not actually show progress.

  • Threading and mutexes are now done with (C++11) the stdlib. This decreases the dependency on Boosts.

  • Fixed gcc 7.3 compilation: pow10 was removed from gcc 7.3 (glibc 2.27).

  • Fixed unit weighting to not include flagged/unavailable visibilities during imaging when used.

  • Preparations for IDG A-term correction: no longer store visibilities preweighted, pass full weighting to IDG.

  • Do output errors in quiet mode.

  • Don’t allow rectangular images when IDG is enabled.

  • Improved readability of non-verbose mode a bit; be less verbose for sets with denormal phase centre and removed some other technical output.

  • Reported nr of major iterations was one too high (on cmdline as well as in fits hdr).

  • Invalid floating point cmd line parameters are reported as error instead of interpreting them as zero.

  • Independent QU imaging with multiple channels would not clean U: weight was not initialized (reported by R. van Weeren).

  • Also fixing bad keyword ‘WSCMINOR’ in dirty image of second polarization.

  • Lofar beam correction with only-I imaging causes segfault (Identified by A. Shulevski).