hifa_gaincalsnr

hifa_gaincalsnr(vis=None, field=None, intent=None, spw=None, bwedgefrac=None, hm_nantennas=None, maxfracflagged=None) → ResultsList[Results][source]

Compute gaincal signal-to-noise ratios per spw.

The gaincal solution signal-to-noise is determined as follows:

  • For each data set the list of source(s) to use for the per-scan gaincal solution signal-to-noise estimation is compiled based on the values of the field, intent, and spw parameters.

  • Source fluxes are determined for each spw and source combination.

  • Fluxes in Jy are derived from the pipeline context.

  • Pipeline context fluxes are derived from the online flux calibrator catalog, the ASDM, or the user via the flux.csv file.

  • If no fluxes are available the task terminates.

  • Atmospheric calibration and observations scans are determined for each spw and source combination.

  • If intent is set to 'PHASE' are there are no atmospheric scans associated with the 'PHASE' calibrator, 'TARGET' atmospheric scans will be used instead.

  • If atmospheric scans cannot be associated with any of the spw and source combinations the task terminates.

  • Science spws are mapped to atmospheric spws for each science spw and source combinations.

  • If mappings cannot be determined for any of the spws the task terminates.

  • The median Tsys value for each atmospheric spw and source combination is determined from the SYSCAL table. Medians are computed first by channel, then by antenna, in order to reduce sensitivity to deviant values.

  • The science spw parameters, exposure time(s), and integration time(s) are determined.

  • The per scan sensitivity and signal-to-noise estimates are computed per science spectral window. Nominal Tsys and sensitivity values per receiver band provide by the ALMA project are used for this estimate.

  • The QA score is based on how many signal-to-noise estimates greater than the requested signal-to-noise ratio can be computed.

Parameters:

  • vis --

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

    Example: vis=['M82A.ms', 'M82B.ms']

  • field --

    The list of field names of sources to be used for signal to noise estimation. Defaults to all fields with the standard intent.

    Example: field='3C279'

  • intent --

    A string containing a comma-delimited list of intents against which the selected fields are matched. Defaults to 'PHASE'.

    Example: intent='BANDPASS'

  • spw --

    The list of spectral windows and channels for which gain solutions are computed. Defaults to all the science spectral windows for which there are both 'intent' and TARGET intents.

    Example: spw='13,15'

  • bwedgefrac --

    The fraction of the bandwidth edges that is flagged.

    Example: bwedgefrac=0.0

  • hm_nantennas --

    The heuristics for determines the number of antennas to use in the signal to noise estimate. The options are 'all' and 'unflagged'. The 'unflagged' options is not currently supported.

    Example: hm_nantennas='unflagged'

  • maxfracflagged --

    The maximum fraction of an antenna that can be flagged before it is excluded from the signal to noise estimate.

    Example: maxfracflagged=0.80

Returns:

The results object for the pipeline task is returned.

Examples

1. Estimate the per scan gaincal solution sensitivities and signal to noise ratios for all the science spectral windows:

>>> hifa_gaincalsnr()