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Package | synthesis | |
Module | calibrater | |
Tool | calibrater |
This function can be used to correct the gains derived from secondary
calibrators with unknown or variable polarization. It should only be
used for arrays with linear (X/Y) feeds and an Alt-Az mount for which
the observed polarization varies with feed position angle on the sky.
The function fits the gains with a sine and cosine term in feed position
angle and extracts the Q and U components of the secondary calibrator.
This is only possible if there is sufficient range in the position angle
(i.e., minimum of about 6 scans spanning at least 90 degrees in position
angle). Check the error of the fit to judge if the fit was succesfull,
it should generally be smaller than 0.5%.
Use the fields argument to select calibrator fields to be
fitted. The function takes a calibration table as input, and can write
the adjusted gain solutions to the same table on output, or create a new
table containing these results. The function also prints the derived
polarization for each field for each spectral window.
This example takes an existing calibration table containing G
Jones matrices, and writes a corrected output table, correcting only
gains derived from 2254-367 for linear polarization.
Correct the gain table for linear polarization of the calibrator
Synopsis
linpolcor(tablein, tableout, fields)
Arguments
tablein
Input calibration table name
Allowed:
String
Default:
''
tableout
Output calibration table name
Allowed:
String
Default:
''
fields
Calibrator field names
Allowed:
Vector of strings
Default:
""
Returns
Bool
Description
Example
c:=calibrater('atca.ms');
c.linpolcor(tablein='atca.gcal', tableout='atca.gcal2',
fields='2254-367');
c.done();
Next: calibrater.plotcal - Function
Up: calibrater - Tool
Previous: calibrater.calave - Function
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