JACKS weblog review guide
Very useful QA guidelines from ACES: https://github.com/ACES-CMZ/reduction_ACES/wiki/ACES-data-QA-guide
Useful NRAO Weblog Guide: https://casaguides.nrao.edu/index.php/VLA-S-CASA_Pipeline-CASA6.5.4#By_Task_Screen:_Overview_of_the_Pipeline_Heuristic_Stages
Showcase: https://github.com/ACES-CMZ/reduction_JACKS/issues/10
Weblog: https://mills.ku.edu/JACKS/2022_12_20_T22_25_18.828/pipeline-20221220T225107/html/
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Some useful information:
- Project code, PI name, observation start/end time, CASA/pipeline version (and the environment)
- QA notes from the NRAO staff, potentially useful are the ‘Issues noted but not flagged by staff’.
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If there are multiple executions, we should see a summary for each of them. For JACKS, we only have a single execution for each scheduling block. Click into the execution link and you will find a lot of information about the observation, which may be useful later.
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For example:
- Click on the ‘listobs output’ and see the content of the ‘listobs’ file.
- Click on the ‘Spatial Setup’ to see the coordinates of the pointings.
- Click on the ‘Antenna Setup’ to see the locations of the antennas, the uv coverage, and the baseline statistics.
Highlights of errors/warnings during the pipeline run
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We can check the pipeline tasks step by step in the third tab ‘By Task’. Here it may be useful to look at the flagging summary:
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- Data flagged in the amp/bandpass calibrator 3C286: antennas ea08 and ea26. Then for the phase calibrator J1744 and the science targets, data from these two antennas cannot be calibrated, and have to be flagged.
- For the phase calibrator J1744, in general the flagging fraction is <50%. Some antennas have higher flagging fractions (>50%), e.g., ea01, ea14, ea15, ea22, ea27. This likely leads to additional flagging for the science targets, because the science targets have to be bracketed by observations of phase calibrators, and if any phase calibration data were flagged, then the science target data in between have to be flagged as well. Scroll down and you will find science targets data of these antennas are flagged.
The most important/tricky part of the weblog review.
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Things to look out for:
- Low QA scores (red/orange bars), errors and warnings
- Calibration solutions in ‘13. hifv_finalcals’, and diagnostic plots in ‘17. hifv_plotsummary’.
Rule of thumb: everything should be almost flat.
- The most important one could be ‘Final phase gain cal’.
- Unusually large fractions of flagging.
- Calibrator images in ‘19. Hif_makeimages (cals)’.
- Are the calibrators point sources with the same shape as the beam? Are the ‘pbcor image max’ values consistent with the fluxes of the calibrators (from steps 4 & 12)?
- What is the beam size of the phase calibrator image? (This probably would be the beam size for our science target)
Examples:
- This plot in 17, an antenna shows strange behavior in phase vs. frequency (the yellow dots): bad bandpass solutions for this antenna?
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- In ‘15. RFI Flagging’: If a file with continuum regions is specified, then the task will only flag those spw and frequency ranges per the pipeline spectral line heuristics. – is this what we need for skipping RFI flagging in the pipeline?
- How to plot phase vs. time in step 17?
- Any errors (and warnings if you believe they are important) in ‘By Task’: note the step number, post screenshots or copy&paste the error/warning messages.
- Any unusual behaviors in the plots in steps 13 and 17, e.g., curves not flat, outliers: post screenshots and note the step number, and note the antenna/spw id if possible.
- Any unusually large fractions of flagging: note the flagged source name (BP cal, phase cal, or the science targets) and antenna/spw id, and post screenshots.
- Anything else that is unusual/suspicious: briefly describe the issues and post screenshots if possible.
- Don’t worry when you are not sure if it is ‘unusual’ or not, just comment on it whenever you have questions, and we will discuss it together in our DR meetings…