Correcting the observed data

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Next: Extending calibration to bandpass, polarization, etc. Up: Practical use of the calibrater tool Previous: Establishing the flux density scale

Correcting the observed data

The observed data, which are stored in the DATA column, are corrected by using the Calibrater.setapply function to specify the calibration tables to be used, the interpolation intervals and any selection which is to be applied to the calibration tables as they are read into AIPS++. This function, in conjunction with the selection which can be applied to the MS itself via the Calibrater.setdata, allow cross-calibration. The actual application of the corrections is performed using the Calibrater.correct function, which takes no further parameters. Note that this function must be called explicitly if the corrections are to be applied; this does not occur by default after solving for a set of calibration effects.

To apply the scaled 'G' calibration obtained above:

cal := calibrater('polspec.ms')          # Construct
cal.setdata(msselect='FIELD_ID==4')      # Select data to which calibration will be applied:
#
cal.setapply(type='P', t=5.0)            # arrange to apply P (unnecessary if cal tool not reset)
cal.setapply(type='G', t=0.0,            # arrange to apply G table, solutions from source 1:
             table='polspec.fluxscale',
             select='FIELD_ID==1')
#
cal.correct()                            # apply solutions, writing CORRECTED_DATA column:
cal.done();

Application of solutions from other calibrators to other target sources would be done by setting the selection parameters in Calibrater.setdata and Calibrater.setapply appropriately. Muliple sources may be specified in either selection.

Next: Extending calibration to bandpass, polarization, etc. Up: Practical use of the calibrater tool Previous: Establishing the flux density scale Contents