Atacama Large Millimeter/submillimeter Array

Karl G. Jansky Very Large ArrayRobert C. Byrd Green Bank Telescope

Very Long Baseline Array

CASA Progress and StatusANASAC Face-to-FaceSept 16-17, 2013

Jeff KernCASA Team Lead

ALMACASA Status• CASA is in routine use at ALMA and the VLA for daily

operations.– Many other observatories are also using CASA

• 25% of NRAO CASA Helpdesk tickets are for non-NRAO telescopes

• Improvement in performance, ease of use, and robustness are being addressed as well as the development of additional features.

• Reviewed in March: – Report and response available:

• https://safe.nrao.edu/wiki/bin/view/Software/CASA/WebHome

– Summary: • Remain focused on VLA and ALMA needs• Improve fundamentals of software engineering

process2ANASAC Face-to-Face: Sept. 16,17 2013

ALMAOrganization Changes• In the process of organizing a new CASA Users Committee

to solicit input from a wider segment of the CASA users community.– Details still in progress– Designed to complement the CASA Science Steering

Committee (CSSC) not replace.

• We are working closely with Science User Support (SUS) to do scientific validation of new CASA features prior to release.– Bi-weekly meeting to review test targets, status and

assignments

• DMSG has added a software testing group focused on ALMA testing, including CASA:– Focused on improving automated software testing, not

validation.

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ALMACASA Usage• CASA Releases are downloaded around 2000 times per

release– Widely distributed download sites

• Weak preference for ALMA partners

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CASA-3.2CASA-3.3CASA-3.4CASA-4.0CASA-4.1

ALMAPerformance• CASA performance for most tasks is comparable with other

packages.– Historical reputation for performance issues still linger.– Are some known poorly performing capabilities (plotting)

• Parallel CASA has been demonstrated to significantly improve performance.– User interface issues / learning curve have prevented

wide acceptance• Moving from home grown cluster management to MPI

• Working with Scientific Computing Infrastructure group to benchmark pipelines and identify performance bottlenecks.

• MSTransform task introduced:– Allows multiple actions on data with a single read from

disk.– Consolidates duplicate code to single maintainable

framework.5

ALMAPerformance: Data Access (Disk I/O)• Unlike many other aspects of the processing equation, time

alone will not solve the data access problem.

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EVLA Data Size System Memory Disk Volume CPU Performance Disk I/O rate

ALMA

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Performance Comparison

• Very simple imaging to try to minimize package variations

• All tests run on Socorro cluster node against Lustre

CASA Review March 5-6. 2013

– 4000 X 4000 pixels– 3000 Components– No Boxing– 0.5 arcsec– Number of Terms = 1

– Single pointing– No Widefield– No A-Term– Briggs weighting 0

• Time to Image ~200 GB data set:

ALMA

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Performance Comparison

CASA Review March 5-6. 2013

CASA MIRIAD AIPS

1 Major CycleSerial 88 112

1 Major CycleThreaded 55

5 Major Cycles Serial 333 270

5 Major Cycles Threaded 216

5 Major Cycles Multi-process 74

All times in Minutes

ALMAInfrastructure Initiatives• Continued effort on Parallelization, focused on delivery of

capabilities to end users/• MSTransform to standardize I/O and decrease overall I/O

volume• Imager Update

– Major re-architecting to improve interface, normalize options, support for new algorithms, regularization.

• Region Format: Unification and improvement across the package.

• Tool Documentation: Image tool is current focus, starting to work our way through the package.

• Imregrid: Major rework for more intuitive operation.• SetJy: Reorganized for more clarity in options, scriptability

(pipeline), and improved capabilities.9

ALMARecent Developments

• Support for Linear Polarized Feeds (Required for ALMA Cycle-2)

• Support for rapidly moving objects (Ephemeris Objects) throughout package

• Simulation update in support of Cycle-2 CFP• Improved primary beam handling

– Summer student Kara Kundert has extended her project to understand the effects of heterogeneous primary beams on image dynamic range.

• Single Dish:– Introduction of CalTable like interface (Pipeline Support)– Performance Improvements

• Feathering: Capability is undergoing continued enhancements

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ALMACASA Viewer

• Many improvements in the CASA viewer– Histogram generation and fitting– Spectral line display and fitting– Position-Velocity Curves– Interface improvements

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ALMACASA ViewerPrimary View

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ALMACASA Viewer:Spectral Line Fitting

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ALMACASA ViewerHistogram fitting

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ALMAALMA Development Program• CASA was very active in the ALMA Development program• Studies:

– NRAO PI: Interoperability of AstroPy and CASA• Projects:

– NRAO PI: [Sub-]Millimeter VLBI support in CASA– NRAO PI: Extended On Demand Computing

• CASA Execution in external environments XSEDE– NRAO CO-I: Post imaging Analytics

• Development of “value added” products for the pipeline

– NRAO CO-I: Next Generation Viewer• Collaborating on a Tera-Pixel viewer

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The National Radio Astronomy Observatory is a facility of the National Science Foundation

operated under cooperative agreement by Associated Universities, Inc.

www.nrao.edu • science.nrao.edu