FAQ
Keywords: pdbi-cookbook

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FAQ

How to proceed to repeat a calibration step? If you want to repeat a part of the calibration, you do not need to repeat all the calibration steps happening before, but those taking place later according to the scheme here described. Note that clicking on `Select` (within the `Standard Calibration` widget) is always recommended before repeating any calibration step, in order to have proper settings.

How can I mask flagged data? Sometimes procedures crash because a lot of data of an antenna or baseline are flagged. We can verify the kind of flags with the command ``list /flag''. We can mask them with the command ``mask flag_label /ant i'' (or ``/baseline ij''). For example, ``mask shadow /ant 3'' would mask the flags of antenna 3 (logical) due to shadowing. Masking flags without a clear understanding of what it means is not recommended. However, masking certain calibrator flags may be convenient in some cases (see Sect. , and ). If flagged data are masked in some part of the calibration, the masking should be reset with ``mask /reset'' (e.g. ``mask shadow /ant 3 /reset'') at the end of the calibration step.

Is there any command in CLIC that refers to physical antennas? No. The physical antenna numbers are just shown in the plots of the `First Look` procedures, because the command ``plot /physical'' is the default there. Otherwise, all CLIC commands and procedures use the logical numbers for antennas. This must be taken into account if AoD notes refer to physical antennas, or when applying a new baseline model in observations with an incomplete array.

How can I flag data? After selecting the data to be flagged with ``find'', you can use the command ``store flag flag_label /ant i'' (or ``/baseline ij''). We can also delete them by changing their quality with the command ``store quality 9 /ant i'' (or ``/baseline ij''). Please, ask your local contact if any doubt.

For example, the following commands would allow flagging correlations obtained with all antennas on a source of name starting by 1823, between the scans 234 and 250, with the label ``redu'':
`CLIC> find /proc corr flux /sou 1823* /scan 234 250
CLIC> store flag redu /ant all
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Next: Other calibration procedures Up: Standard Calibration Previous: Usual difficulties Contents