pipeline.hifa.cli.hifa_gfluxscale

hifa_gfluxscale(vis=None, reference=None, transfer=None, refintent=None, transintent=None, refspwmap=None, reffile=None, phaseupsolint=None, solint=None, minsnr=None, refant=None, hm_resolvedcals=None, antenna=None, peak_fraction=None, amp_outlier_sigma=None, parallel=None) → ResultsList[Results][source]

Derive flux density scales from standard calibrators.

Derive flux densities for point source transfer calibrators using flux models for reference calibrators.

Flux values are determined by:

  • computing phase-up solutions for all the science spectral windows using the calibrator data selected by the reference and refintent parameters and the transfer and transintent parameters, with solint and gaintype parameters, and spw mapping or combination as determined in hifa_spwphaseup. If no solint is defined, phaseupsolint is used (default = 'int').

  • computing amplitude only solutions for all the science spectral windows using calibrator data selected with reference and refintent parameters and the transfer and transintent parameters.

  • examining the amplitude-only solutions for obvious outliers and flagging them in the caltable.

  • transferring the flux scale from the reference calibrators to the transfer calibrators using refspwmap for windows without data in the reference calibrators.

  • inserting the computed flux density values into the MODEL_DATA column.

Resolved calibrators are handled via antenna selection either automatically (hm_resolvedcals = 'automatic') or manually (hm_resolvedcals = 'manual'). In the former case, antennas closer to the reference antenna than the uv distance where visibilities fall to peak_fraction of the peak are used. In manual mode, the antennas specified in antenna are used.

Note that the flux corrected calibration table computed internally is not currently used in later pipeline apply calibration steps because the relevant calibrator flux densities have been set in the MODEL_DATA column.

Note that for very low SNR, noise bias already positively skews the amplitudes. The time solint could be greater for either transintent or refintent, which has a compounding effect: if the phase stability is insufficient over that longer solint, an optimal phaseup will not be able to be calculated, and this also results in an artificial increase in amplitudes because the amplitude gains compensate for the uncorrected decorrelation.

Parameters:

  • vis --

    The list of input MeasurementSets. Defaults to the list of MeasurementSets specified in the pipeline context.

    Example: ['M32A.ms', 'M32B.ms']

  • reference --

    A string containing a comma delimited list of field names defining the reference calibrators. Defaults to names of fields with intents in refintent.

    Example: reference='M82,3C273'

  • transfer --

    A string containing a comma delimited list of field names defining the transfer calibrators. Defaults to names of fields with intents in transintent.

    Example: transfer='J1328+041,J1206+30'

  • refintent --

    A string containing a comma delimited list of intents used to select the reference calibrators. Defaults to 'AMPLITUDE'.

    Example: refintent='', r``efintent='AMPLITUDE'``

  • transintent --

    A string containing a comma delimited list of intents defining the transfer calibrators. Defaults to 'PHASE,BANDPASS,CHECK,DIFFGAINREF,DIFFGAINSRC,POLARIZATION,POLANGLE,POLLEAKAGE'.

    Example: transintent='', transintent='PHASE,BANDPASS'

  • refspwmap --

    Vector of spectral window ids enabling scaling across spectral windows. Defaults to no scaling.

    Example: refspwmap=[1,1,3,3] - (4 spws, reference fields in 1 and 3, transfer fields in 0,1,2,3)

  • reffile --

    Path to a file containing flux densities for calibrators. Setjy will be run for any that have both reference and transfer intents. Values given in this file will take precedence over MODEL column values set by previous tasks. By default, the path is set to the CSV file created by hifa_importdata, consisting of catalogue fluxes extracted from the ASDM and / or edited by the user.

    Example: reffile='', reffile='working/flux.csv'

  • phaseupsolint --

    Time solution intervals in CASA syntax for the phase solution.

    Example: phaseupsolint='inf', phaseupsolint='int', phaseupsolint='100sec'

  • solint --

    Time solution intervals in CASA syntax for the amplitude solution.

    Example: solint='inf', solint='int', solint='100sec'

  • minsnr --

    Minimum signal-to-noise ratio for gain calibration solutions.

    Example: minsnr=1.5, minsnr=0.0

  • refant --

    A string specifying the reference antenna(s). By default, this is read from the context.

    Example: refant='DV05'

  • hm_resolvedcals -- Heuristics method for handling resolved calibrators. The options are 'automatic' and 'manual'. In automatic mode, antennas closer to the reference antenna than the uv distance where visibilities fall to peak_fraction of the peak are used. In manual mode, the antennas specified in antenna are used.

  • antenna --

    A comma delimited string specifying the antenna names or ids to be used for the fluxscale determination. Used in hm_resolvedcals='manual' mode.

    Example: antenna='DV16,DV07,DA12,DA08'

  • peak_fraction -- The limiting UV distance from the reference antenna for antennas to be included in the flux calibration. Defined as the point where the calibrator visibilities have fallen to peak_fraction of the peak value.

  • amp_outlier_sigma --

    Sigma threshold used to identify outliers in the amplitude caltable. Default: 50.0.

    Example: amp_outlier_sigma=30.0

  • 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. Compute flux values for the phase calibrator using model data from the amplitude calibrator:

>>> hifa_gfluxscale()