pipeline.hif.cli.hif_rawflagchans

hif_rawflagchans(vis=None, spw=None, intent=None, flag_hilo=None, fhl_limit=None, fhl_minsample=None, flag_bad_quadrant=None, fbq_hilo_limit=None, fbq_antenna_frac_limit=None, fbq_baseline_frac_limit=None, parallel=None) → ResultsList[Results][source]

Flag deviant baseline/channels in raw data.

hif_rawflagchans flags deviant baseline/channels in the raw data.

The flagging views used are derived from the raw data for the specified intent - default is BANDPASS.

Bad baseline/channels are flagged for all intents, not just the one that is the basis of the flagging views.

For each spectral window the flagging view is a 2d image with axes 'channel' and 'baseline'. The pixel for each channel, baseline is the time average of the underlying unflagged raw data.

The baseline axis is labeled by numbers of form id1.id2 where id1 and id2 are the IDs of the baseline antennas. Both id1 and id2 run over all antenna IDs in the observation. This means that each baseline is shown twice but has the benefit that 'bad' antennas are easily identified by eye.

Three flagging methods are available:

If parameter flag_hilo is set True then outliers from the median of each flagging view will be flagged.

If parameter flag_bad_quadrant is set True then a simple 2 part test is used to check for bad antenna quadrants and/or bad baseline quadrants. Here a 'quadrant' is defined simply as one quarter of the channel axis. The first part of the test is to note as 'suspect' those points further from the view median than fbq_hilo_limit * MAD. The second part is to flag entire antenna/quadrants if their fraction of suspect points exceeds fbq_antenna_frac_limit. Failing that, entire baseline/quadrants may be flagged if their fraction of suspect points exceeds fbq_baseline_frac_limit. Suspect points are not flagged unless as part of a bad antenna or baseline quadrant.

Parameters:

  • vis -- List of input MeasurementSets. default: [] - Use the MeasurementSets currently known to the pipeline context.

  • spw --

    The list of spectral windows and channels to which the calibration will be applied. Defaults to all science windows in the pipeline context.

    Example: spw='17', spw='11, 15'

  • intent --

    A string containing the list of intents to be checked for antennas with deviant gains. The default is blank, which causes the task to select the 'BANDPASS' intent.

    Example: intent='*BANDPASS*'

  • flag_hilo -- True to flag channel/baseline data further from the view median than fhl_limit * MAD.

  • fhl_limit -- If flag_hilo is True then flag channel/baseline data further from the view median than fhl_limit * MAD.

  • fhl_minsample -- Do no flagging if the view median and MAD are derived from fewer than fhl_minsample view pixels.

  • flag_bad_quadrant -- True to search for and flag bad antenna quadrants and baseline quadrants. Here a /'quadrant/' is one quarter of the channel axis.

  • fbq_hilo_limit -- If flag_bad_quadrant is True then channel/baselines further from the view median than fbq_hilo_limit * MAD will be noted as 'suspect'. If there are enough of them to indicate that an antenna or baseline quadrant is bad then all channel/baselines in that quadrant will be flagged.

  • fbq_antenna_frac_limit -- If flag_bad_quadrant is True and the fraction of suspect channel/baselines in a particular antenna/quadrant exceeds fbq_antenna_frac_limit then all data for that antenna/quadrant will be flagged.

  • fbq_baseline_frac_limit -- If flag_bad_quadrant is True and the fraction of suspect channel/baselines in a particular baseline/quadrant exceeds fbq_baseline_frac_limit then all data for that baseline/quadrant will be flagged.

  • parallel --

    Process multiple MeasurementSets in parallel using the casampi parallelization framework.

    Options: 'automatic', 'true', 'false', True, False

    Default: None (equivalent to False)

Returns:

The results object for the pipeline task is returned.

Examples

  1. Flag bad quadrants and wild outliers, default method:

>>> hif_rawflagchans()

equivalent to:

>>> hif_rawflagchans(flag_hilo=True, fhl_limit=20, flag_bad_quadrant=True, fbq_hilo_limit=8,
...                  fbq_antenna_frac_limit=0.2, fbq_baseline_frac_limit=1.0)