Continued development of continuum imaging pipelines using LOFAR codes (WSClean, DP3, ...)

  During PI11, we encountered the following issues while comparing screen-based and facet-based imaging using WSClean Evaluation of the OSKAR beam in EveryBeam is much slower than evaluation of the LOFAR beam in EveryBeam. This had significant impact on the reported results on computational performance. In screen-based imaging of the SKA-LOW simulated data set, we noticed an unexpected scaling of the flux scale.  In facet-based imaging of the SKA-LOW simulated data set, the deconvolution process diverged. In this time boxed activity to continue development and analysis of SDP imaging pipelines based on DP3, WSClean and IDG, we want to resolve this issue. By the end of PI12, we want to be able to perform simple DI imaging; imaging with correction for known primary beams, both using screen-based and facet-based approaches. In the next PI, a calibration step can be added for either DI or DD effects. In PI11, we also shows parallelisation on a single multi-core node. In this PI, we want to extend that to a multi-node test, ideally aiming for about 8 nodes.   Needs to adhere to the following unless specifically agreed otherwise: Pipelines developed must be easily discoverable (in SKA GitLab), and runnable by others - including sufficient documentation, installation instructions suitable for another SDP pipeline developer to use without needing unreasonable levels of specific knowledge about the code/application in question. Whenever possible, comparisons should be made with other solutions being developed (ie for SP-1905 , SP-1998 , SP-1549 ) and when comparisons are made they should be done using standard tools such as the QA checker. Where these tools are found to be insufficient this ticket should help contribute to improving them and making them available for others to use. Pipeline results should make use of standard SKA simulation data sets (possibly revised in PI12 as part of SP-1901 ).  Development of the pipelines should be regularly shared as part of the Processing Workflows CoP and major results should continue to be demoed at DP System Demos at the earliest opportunity (possibly not waiting until the end of the PI and the closeout of the ticket if a useful and interesting result is found along the way).