hifa_imageprecheck

hifa_imageprecheck(vis=None, desired_angular_resolution=None, calcsb=None, parallel=None) → Results[source]

Select the optimal Briggs robust parameter and compute sensitivity estimates for science targets.

Uses the representative source and spw containing the representative frequency (set by the PI in the OT) to compute synthesized beam and sensitivity estimates for the aggregate and representative bandwidths over a range of Briggs robust values. The WebLog reports a table of beamsize and sensitivity per robust value. If no representative target/frequency information is available the first target and center of the first spw are used (e.g. pre-Cycle 5 data does not have this information available).

The robust value is selected from the range 0.0-2.0 by checking in order: +0.5, +1.0, 0.0, +2.0. Values below 0.0 are not considered (poorer noise characteristics, compromised extended emission recovery). For the ACA 7-m array only robust=+0.5 is considered.

The selected cell and imsize are stored in the pipeline context and reused for all subsequent imaging stages (continuum, cube, representative bandwidth) to ensure consistent image coordinates.

Parameters:

  • vis --

    The list of input MeasurementSets. Defaults to the list of MeasurementSets specified in the hifa_importdata task. '': use all MeasurementSets in the context

    Examples: 'ngc5921.ms', ['ngc5921a.ms', ngc5921b.ms', 'ngc5921c.ms']

  • desired_angular_resolution --

    User specified angular resolution goal string. When this parameter is set, uvtapering may be performed. '': automatic from performance parameters (default).

    Example: '1.0arcsec'

  • calcsb -- Force (re-)calculation of sensitivities and beams; defaults to False

  • parallel --

    Use the CASA imager parallel processing when possible.

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

    Default: 'automatic'

Notes

QA score based on fit between the predicted synthesized beam and the PI-requested angular resolution (AR) range:

  • QA = 1.0 (green): both major and minor axes within the AR range with robust=+0.5.

  • QA = 0.85 (blue): both axes within the AR range with a robust value other than +0.5.

  • QA = 0.50 (yellow): at least one axis outside the AR range but the beam area within the area range corresponding to the PI-requested AR range.

  • QA = 0.25 (red): beam area falls outside the PI-requested AR area range for all robust values, meaning imaging products are unlikely to meet PI goals.

An additional factor of 1.0 vs. 0.5 is applied based on whether representative target/frequency information was successfully identified.

Returns:

The results object for the pipeline task is returned.

Examples

  1. Run with default settings to select the best robust parameter prior to imaging:

>>> hifa_imageprecheck()

  1. Force re-calculation of sensitivities and beams:

>>> hifa_imageprecheck(calcsb=True)