WSClean version 3.4
===================

Released 2023-10-11

Summary: 

Version 3.4 contains a few major new features and important bugfixes. An important change is that the default gridder has been changed to the :doc:`wgridder <../wgridding>`: in *most* cases this gridder is fast and more accurate (thanks to Martin Reinecke) compared to the wstacking gridder -- the previous default gridder. Furthermore, there are quite some changes that improve complex imaging runs (e.g. faceting, DD psfs, IQUV imaging, etc.), memory & computational efficiency was further improved and various bugs have been solved.

To make use of EveryBeam, WSClean 3.4 requires EveryBeam `version 0.5.2 <https://git.astron.nl/RD/EveryBeam/-/releases/v0.5.2>`_ or newer.

Full change list
----------------

* The :doc:`wgridder <../wgridding>` is now the default gridder.
* Add an absolute :doc:`auto mask <../masking>` threshold.
* Facet feathering.
* Support for the MeerKAT and ALMA beams.
* Compression of auto-masks to reduce memory requirements.
* Improve efficiency of data & meta-data reading.
* Allow output of a psuedo-Stokes-I source list.
* Support applying independent xx/yy solutions when imaging Stokes I.
* Support for diagonal and full Stokes solution correction and IQUV imaging with beam.

Bug fixes
---------

* Solve flux-scale issues when using facet imaging with diagonal solutions and beam correction.
* Solve a crash when the model column needs to be created for measurement sets with heterogeneous spws.
* Fix a crash when ``n_spws > 1`` and pb correction is used.
* Improve :doc:`rank filter <../weight_rank_filter>` when using Briggs weighting (issue reported by A. Kutkin and T. Oosterloo).
* Fix :doc:`DD PSF imaging <../direction_dependent_psfs>` with facets and multiple channels.
* Fix possible corruption of start time (as written to FITS file).
* Fix crash in multi-frequency imaging with iquv polarizations and beam correction.
* Allow full Stokes facet imaging with beam and diagonal solutions. 
* Fix a few compilation issues and warnings on specific platforms.
* Documentation improvements.

