Transcript CABB data reduction

CABB Data Reduction Review
Summary of recommendations
Dave McConnell
June 2011
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.
CSIRO. Review of CABB data reduction software
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
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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
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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