hifa_session_refant

hifa_session_refant(vis=None, phase_threshold=None) → Results[source]

Select a single common reference antenna per session for polarization observations.

Re-evaluates the reference antenna lists from all MeasurementSets within a session and selects a single common reference antenna per session to be used by all subsequent pipeline stages.

The selection algorithm:

  1. Rank all antennas by the product of their per-EB rankings (based on flagging fraction and central location in the array, as in hif_refant).

  2. Starting from the highest-ranked antenna, perform a gaincal with solint='int', calmode='p', gaintype='G', minsnr=3 on all PHASE intent scans for each EB.

  3. Check the resulting caltable to see if the reference antenna ever changes. Choose the first antenna for which no refant changes occur.

  4. If none of the top-3 candidates qualify (which should be rare), choose the antenna with the most solutions as refant and display the number of phase-solution outliers (integrations where the refant phase was non-zero, meaning another refant was used). The total number of possible solutions is N_EBs x N_spws x N_integrations x N_pol.

If a single refant was requested via hif_refant in the PPR, a warning is generated indicating that only one antenna is common across all MSes.

Parameters:

  • vis --

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

    Example: vis=['ngc5921.ms']

  • phase_threshold --

    Threshold (in degrees) used to identify absolute phase solution outliers in caltables.

    Example: phase_threshold=0.005

Notes

QA = 1.0 if a suitable session reference antenna is found, otherwise 0.0.

Only used in polarization recipes.

Returns:

The results object for the pipeline task is returned.

Examples

  1. Compute a single common reference antenna per session:

>>> hifa_session_refant()