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6 Phase calibration

The main part of phase calibration is ``fringe-fitting'' whereby the phase derivatives with respect to frequency and time are solved for and removed from the data. As with the amplitude calibration the tables from the user pipeline can be used (CL3), but it may be beneficial to fringe-fit the data yourself, for example after having rigorously flagging the data (the data flagging within the pipeline is unavoidably crude).

A potentially important step for both phase-referencing and polarisation experiments is the removal of the parallactic angle. Since January 2003, this is performed by the pipeline on all experiments, the corrections being written into CL2 (amplitude calibration). If you use the pipeline table CL2, then the following steps should be applied to this table to make CL3. If, however, you have made your own version of CL2, then you also have to apply the parallactic angle correction as described in Appendix B.


Stefanie Muehle 2008-01-28