CABB Data Reduction Review Summary of recommendations Dave McConnell June 2011

CSIRO. Review of CABB data reduction software Review of CABB data reduction Review panel Mark Wieringa (Chair), Mark Calabretta, Dave McConnell, Tim Corwell, Bjorn Emonts, Emil Lenc, Jamie Stevens, Maxim Voronkov Aim Survey state of main reduction packages relevant to CABB data. Provide recommendations for the way forward.

Terms of Reference Will Miriad continue to be the main reduction package for ATCA data for the next 5 years? Does the combination of Miriad and ASKAPsoft enable all foreseeable ATCA data sets to be optimally reduced? Should ATCA data reduction with CASA be actively tested and documented? Should CASS consider contributing to CASA development? What data reduction functionality is missing? How do the items rank in order of scientific priority? How can the missing functionality be provided most easily, given the re- sources? CSIRO. Review of CABB data reduction software

Will Miriad continue to be the main reduction package for ATCA data for the next 5 years? Yes except for some special imaging and analysis problems it is the most efficient package for the bulk of data reduction Rise of ALMA will result in more experienced CASA users Point of departure from Miriad may move earlier After calibration After uvsplit CSIRO. Review of CABB data reduction software

Miriad+ASKAPsoft = optimal reduction? No, not at present Some effort towards this would pay off Keeps expertise “in house” ASKAPSoft is not a general user package Priority: pipeline processing of very large data volumes on special hardware But: being able to test with CABB data is helpful for both ATCA and ASKAP Use of CASA required Import data Image display & analysis Selfcal CSIRO. Review of CABB data reduction software

Should ATCA data reduction with CASA be actively tested and documented? Yes Skip calibration path – Miriad better at this Advantages Complex imaging and deconvolution Multi-Scale Clean MFS (under development) Automated clean boxes Document Import of calibrated Miriad data Run multi-scale deconvolution algorithms Self calibration Image inspection CSIRO. Review of CABB data reduction software

Should CASS consider contributing to CASA development? No, not at present; review when ASKAP operational ASKAPSoft imaging algorithm developments will appear in CASA over time No resources available for further involvement at this stage CSIRO. Review of CABB data reduction software

What data reduction functionality is missing? Ranked by scientific priority Priority 1 Multi-scale clean Multi Frequency synthesis with non linear terms UV based Clean, UV modelling Priority 2 Spectral curvature (band pass calibrator) Delay calibration (residual phase slopes across band) Polarization leakage – freq dependence Primary beam variation with frequency The rest Image size limits, flagging, peeling, automatic clean boxes, invert weighting errors, polarization imaging/analysis (RM synthesis) CSIRO. Review of CABB data reduction software

How can the missing functionality be provided most easily, given the resources? Use CASA and ASKAPSoft for the complex problems MSClean (multi-scale) available in CASA and ASKAPSoft, including mosaicing, works well MFS Clean Miriad approach works well for single fields CASA – work in progress – wait for next release ASKAPSoft has MS-MFS Clean – testing in progress UV based clean major cycles – subtract from uv data Provided in CASA and ASKAPSoft, results better than image domain clean. Wide band primary beam response Use MFClean for single field Use A-projection in ASKAPSoft for mosaicing CSIRO. Review of CABB data reduction software

Proposed work CSIRO. Review of CABB data reduction software

Recommendations Do a number of small improvements to Miriad A few months worth of development & documentation Documentation of path to CASA and ASKAPSoft Data export from miriad, conversion to MeasurementSet Recipes and scripts for CASA and ASKAPSoft reduction MS Clean – single field, mosaic (CASA) MSMFS Clean – single field, mosaic (ASKAPSoft) RM imaging in CASA CSIRO. Review of CABB data reduction software