National Radio
Astronomy Observatory

4.4.1.3 Prior Calibration and Correction: parang, gaincurve and opacity

These parameters control the on-the-fly application of various calibration or effect-based corrections prior to the solving process.

The parang parameter turns on the application of the antenna-based parallactic angle correction (’P’) in the measurement equation. This is necessary for polarization calibration and imaging, or for cases where the parallactic angles are different for geographically spaced antennas and it is desired that the ordinary gain calibration not absorb the inter-antenna parallactic angle phase. When dealing with only the parallel-hand data (e.g. RR, LL, XX, YY) for a co-located array (e.g. the VLA or ALMA), you can set parang=False and save some computational effort. Otherwise, set parang=True to apply this correction.

There are two control parameters for applying Prior Calibration:

See § 4.3 for more on Prior Calibration.

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