Calibration

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1.6.3 Calibration

The major calibration tasks are:

setjy — Computes the model visibilities for a specified source given a flux density or model image, knows about standard calibrator sources (§ 4.3.4);
gencal — Creates a calibration table for known delay and antenna position offsets (§ 4.3.5);
bandpass — Solves for frequency-dependent (bandpass) complex gains (§ 4.4.2);
gaincal — Solves for time-dependent (frequency-independent) complex gains (§ 4.4.3);
fluxscale — Bootstraps the flux density scale from standard calibrators (§ 4.4.4);
polcal — polarization calibration (§ 4.4.5);
applycal — Applies calculated calibration solutions (§ 4.6.1);
clearcal — Re-initializes calibrated visibility data in a given measurement set (§ 4.6.3);
listcal — Lists calibration solutions (§ 4.5.2);
plotcal — Plots (and optionally flags) calibration solutions (§ 4.5.1);
uvcontsub — carry out uv-plane continuum subtraction for spectral-line data (§ 4.7.5);
split — write out a new (calibrated) MS for specified sources (§ 4.7.1);
cvel — Regrid a spectral MS onto a new frequency channel system (§ 4.7.6).

During the course of calibration, the user will specify a set of calibrations to pre-apply before solving for a particular type of effect, for example gain or bandpass or polarization. The solutions are stored in a calibration table (subdirectory) which is specified by the user, not by the task: care must be taken in naming the table for future use. The user then has the option, as the calibration process proceeds, to accumulate the current state of calibration in a new cumulative table. Finally, the calibration can be applied to the dataset.

Synthesis data calibration is described in detail in Chapter 4.

   1.6.3.1 Prior Calibration
   1.6.3.2 Bandpass Calibration
   1.6.3.3 Gain Calibration
   1.6.3.4 Polarization Calibration
   1.6.3.5 Examining Calibration Solutions
   1.6.3.6 Bootstrapping Flux Calibration
   1.6.3.7 Correcting the Data
   1.6.3.8 Splitting the Data
   1.6.3.9 UV Continuum subtraction
   1.6.3.10 Transforming the Data to a new frame

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